I come from three generations of Anglican clergy.
Half a century ago, my father was parish priest here in Suffolk.
He was a good and faithful priest, much loved by his congregation.
My family lived in a huge Georgian rectory just up the hill from here.
When my father retired, the Church sold the house.
Now the parson lives in another village
and there has been a woman priest in charge, and that would have surprised my father 50 years ago.
His was still the Church of Christendom
which had endured since the time of the Emperor Constantine the Great.
But even as a boy, I could see that the sort of church and society he served was dying.
Now I'd describe myself not so much as a Christian, but as a candid friend of Christianity.
My own life story makes me a symbol of something distinctive about Western Christianity - a scepticism,
a tendency to doubt, which has transformed Western culture and transformed Christianity.
Where did that change come from?
In our final programme we try to understand recent Christian history and where it goes next.
For 2,000 years the Christian answer to the big questions of existence
was faith in God as revealed in Jesus Christ.
That made sense of life and death.
It taught right from wrong.
But the recent history of Christianity has been described
as a sea of faith ebbing away before the relentless advance
of science, reason and progress.
It's actually a much more surprising story.
The tide of faith, perversely, flows back in,
for Christianity has a remarkable resilience.
In crisis, it's rediscovered deep and enduring truths about itself.
And that may even be a clue to its future.
I've lived in Oxford since 1995, Fellow of St Cross College and professor in the theology faculty.
'Our local pub is the Eagle and Child,
'which can actually claim a bit part in Christian history, and not just because I drink here.
'Around the time I was growing up in Suffolk,
'this was the regular haunt of writers CS Lewis, JRR Tolkien and their friends.
'Devout Christians though they were, these writers were asking questions about their faith.'
Thank you very much.
'When CS Lewis published a collection of essays on Christian themes
'he gave it the title, God In The Dock.
'That's a good description of the way in which Western culture
'has increasingly put the Christian God on trial.'
Of course, doubt is a fundamental part of religion -
the Bible's full of it.
The Old Testament is shot through with doubt,
though in its stories doubters tend to feel God's wrath,
like Adam and Eve when they doubted that it was a really bad idea
to eat from the tree of the knowledge of good and evil.
But something odd happened in Western Europe.
Doubt has chipped away at the very fabric of Christianity, Catholic and Protestant,
at times threatening to dynamite its foundations.
We can trace this scepticism back to the period known as the Enlightenment,
when western Europeans began posing questions about the power of monarchs, the power of clergy,
above all, the power of God.
Conventional wisdom has us believe that
the Enlightenment began with the French philosophes in the elegant salons of 18th-century Paris.
But I'll show you that it was in Amsterdam 100 years earlier that God was first put in the dock.
In the 17th century, Amsterdam boasted an economic and social tolerance unequalled in Europe.
This was a proud and cosmopolitan boomtown,
a paradise for traders, but also a marketplace for ideas.
A place where people sought refuge from religious and political persecution.
A brilliant young philosopher who lived in the city was to change the rules of Western religion.
Baruch Spinoza belonged to a well-established refugee community here.
They were Sephardic Jews who had been expelled from
Spain and Portugal after the fall of Muslim Granada in 1492.
This was their synagogue, once at the heart of a thriving, tolerated Jewish Quarter.
You get a sense of the excitement that these people must have felt,
that suddenly they could build, just like a mainstream community.
Here they are, free at last.
Coming from England, this building is pleasingly familiar.
It's just like one of the parish churches which Sir Christopher Wren was building in London
at the same time in the 1670s. You've got all the elements.
You've got the galleries, the dark woodwork, the whitewash,
those great, clear windows with the light streaming in.
And yet, of course, it's also Dutch.
A lovely touch, I think, is on the floor.
Sand, to deaden the sound as people shuffle in.
For many Jews, coming to Amsterdam meant rediscovering the riches of
their tradition, building a beautiful synagogue like this.
But other refugees remembered their sufferings.
They remembered the Spanish Inquisition.
For them, all religion became tainted by the same crazy dogmatism which had fuelled the Inquisition.
Baruch Spinoza felt like
that, and he went so far as to question faith itself.
He did not believe in God as a supernatural, divine being.
Nor did he believe in the immortality of the soul, or the existence of miracles.
Yet Spinoza's God hadn't disappeared from the world entirely.
For Spinoza, God and nature were one.
The philosopher was a gentle, courteous, austere figure
who made his living grinding lenses for spectacles.
But to his enemies he was an evil monster.
In 1656 his relations with the Amsterdam Jewish community reached breaking point.
He refused an offer of 1,000 florins to keep quiet.
At the age of 24 he was expelled from the Amsterdam synagogue without possibility of return.
This is actually the order for his expulsion, "Contra Baruch Espinoza."
"Against Baruch Spinoza."
At the time, Jews and Christians alike thought his views blasphemous and heretical.
But that didn't stop him writing, even though his chances of getting published were slim.
In fact his most startling work only appeared after his death in 1677.
This book is the first edition in Dutch of the writings of Spinoza.
Very brave Dutch publisher to publish this as early as 1677.
But still not brave enough to put Spinoza's full name on the title page.
It's too controversial, so just BDS - Baruch de Spinoza.
I see Baruch Spinoza as the original doubter,
the man who first dared to break with the past and question whether God was the answer.
This was the beginning of that special phenomenon of the Western Enlightenment, an open scepticism
as to whether there can be definitive truths in sacred books.
In his lifetime Spinoza was treated as a dangerous eccentric.
A contemporary of his in England also raised fundamental doubts about the nature of God...
..but he is celebrated as a national hero.
His enquiries were in a field which they called natural philosophy.
It's what we call science.
Up until the 17th century, if you were really clever you had studied theology.
Now, natural philosophers looked at heaven and earth and explained them,
not through the Bible, but through observation.
They set up their own college of research in London
which became The Royal Society, and its most illustrious President was Sir Isaac Newton.
There's a famous tale about Newton's breakthrough in physics.
He's said to have been hit on the head by an apple,
and the apple led him to question the common understanding of God and the universe.
Here is the first real biography of Newton, written by William Stukeley,
and there's that splendid story about the apple and gravity.
That's right. There are actually various versions of this story,
one of which involves a leaf falling from a tree, but I think an apple,
because of its biblical associations,
might well have appealed to Newton more as a good story.
I see, so he's moulding a scientific discovery in the pattern of a biblical story?
That's right and of course, he's also moulding a Newton mythology.
Newton is celebrated as a hero of science, but in no way was he an enemy of religion.
Like Spinoza, he radically rethought it.
He took the Bible very seriously, but on his own terms.
He spent as much energy brooding on the prophecies
of the Last Days in the Book of Revelation as he did on the nature of gravity.
And he insisted that the universe was run
by laws laid down by the Creator God
who had then made the decision to leave the world to its own devices.
Newton's God was becoming different from the God of the Bible.
For one thing, his God was rational, like a natural philosopher, and perhaps for the time being,
just as shut away in his study or laboratory, whatever he might do at the end of time.
There were plenty of people, including churchmen in rational,
practical Protestant England, who thought that what Isaac Newton said made sense.
Perhaps that's because, unlike Spinoza, he kept some of his wilder ideas to himself.
But in Catholic France, the same thoughts had a very different impact.
Here it wasn't just God who was put in the dock.
It was also the Catholic Church.
In the coffee houses of 18th-century Paris, you could meet a new kind of philosopher.
These were men of the world - journalists, playwrights and critics
- and they were united in their hatred of the prejudice and fanaticism
which they saw all around them in the in the sacred monarchy of France.
Their king was an absolute monarch who insisted
that his power came from God and expected the Church to agree.
Since the reign of Louis XIV, a particularly intolerant version of Roman Catholicism had triumphed.
With that background, the philosophes emphasised ever more fiercely
the need for religious toleration, freedom of thought and equality.
Take the best-known name of them all, Voltaire -
the pen-name of Francois Marie Arouet, a French notary's son who just couldn't stop writing.
I'm told that he came here to Le Procope every day
and drank 40 cups of a coffee and chocolate mixture.
Amazing he lived to a ripe old age.
When he did die in 1778, aged 84,
he was denied a Christian burial.
Today, Voltaire's remains are laid to rest here in this mausoleum.
The Pantheon. No better symbol of what the Enlightenment might mean.
Because this started life as a very expensive church, built by a French King, Louis XV.
Now God has been banished and the place is a huge holding pen
for the most illustrious corpses in the French Republic.
Voltaire is one of the most famous of the dead in the Pantheon crypt.
Revered as one of the leading prophets of doubt...
he'd waged war against the Catholic Church with brilliant wit and savage irony.
He hated what he saw as its authoritarianism, superstition and dogmatic rigidity.
But beyond that, he also attacked the idea of a just God.
At first, Voltaire subscribed to the idea of a benevolent creator God,
a referee who makes decisions about human morality and justice.
And even in his 70s, he said, "If God did not exist, it would be necessary to invent him."
That does suggest that we need God, but it's still pretty cynical.
However, in his own mind, Voltaire had already condemned God,
his sentence provoked by a horrifying natural disaster
which chose the most incongruous moment to strike.
It happened in Lisbon in 1755. A massive earthquake
caught the whole city in church on a high festival,
candles blazing in every corner.
Churches and people were crushed or burned and soon the whole city was in ruins and on fire.
When survivors struggled to safety on the waterfront,
a massive tsunami rushed towards them.
Thousands were drowned.
Where was a loving God in this monstrous accident?
Voltaire was appalled by those who believed the earthquake to be
part of God's divine plan in a perfect world.
His response was a scathing satirical novel, Candide.
Candide is an innocent fool - that's what his name means.
His tutor is the pointlessly optimistic Dr Pangloss,
whose catchphrase is, "All is for the best
"in the best of all possible worlds."
The story ends with Candide realising just how wrong Pangloss is.
Voltaire is the extreme example of a mood which seems to me to represent
the most special, unusual thing about Enlightenment culture.
It constantly stands back from itself,
scrutinising, comparing, examining objectively from every angle.
No belief is exempt.
Every assumption carries a health warning.
There are many good things about this. It can produce a sanity, a healthy scepticism,
and it produces a self-confidence which has made Western civilisation one of the most dynamic in history.
Ah, formidable. C'est moi.
But as Voltaire himself forcefully suggested,
it's never a good idea to be too optimistic about human beings.
His scepticism, in the wrong hands, was twisted
and used to annihilate God and the whole of Catholic Christianity.
France celebrates the most iconic moment in its history on 14th July.
On that day, in 1789, the storming of the Bastille heralded the beginning of the French Revolution.
All over Europe, there was enthusiasm at the news of revolution.
"Bliss was it in that dawn to be alive,"
was how William Wordsworth remembered it, looking back on his youth.
You could be forgiven, in 1789, for thinking that the ideals of the Enlightenment had been realised.
Liberty, equality and brotherhood were within reach.
But standing in the way were deeply entrenched
social and political privileges embodied in the French monarchy
and those that had supported it for the past 1,500 years -
the aristocracy, of course, but also the Catholic Church.
While the Church had been only an object of ridicule
for the "philosophes",
revolutionaries now had the power actually to strip the Church hierarchy of its land and wealth.
At first, many lower clergy,
who'd been excluded from such wealth and privilege,
enthusiastically backed the revolution in reforming a system with obvious faults.
But relations soon soured when the revolutionaries began confiscating centuries-worth
of Church properties and interfering in Church government far more than the Bourbon monarchy had ever done.
What began as an end to privilege quickly degenerated.
The evolution began to show its dark side.
The snickering scepticism of the French "philosophes"
was seized upon by the revolutionaries and radicalised
against the Church with a scale and speed which was horrifying.
These are the remains of more than 100 priests murdered on 2nd September, 1792.
They were hacked down or shot in the grounds of this Carmelite convent in Paris.
The September massacres spread, and over the next few years, thousands of Catholics were killed
resisting the revolution in the name of their faith.
The revolution tried to destroy Christianity.
Before 1789, there were no fewer than 40,000 French parishes celebrating the Mass.
By 1794, only 150 were left.
The French army seized Rome and imprisoned the Pope, Pius VI.
The revolutionaries even came up with a substitute ideal, one they hoped would inspire people to die
for the revolution in the way that those priests had died for Christ.
This new cause was liberty, equality and fraternity.
And it made up its own new religion, a pick-and-mix from ancient Greece and Rome.
On a stage in Notre Dame, an actress posed as the Goddess of Reason.
She didn't last long. So much for the victory of rationality.
The French Revolution just could not wipe out the hold which Christianity had over people.
In 1799, Napoleon Bonaparte took over the French Republic in a coup d'etat.
And at the centre of his blueprint for the future was a fresh deal with Catholicism.
Napoleon had grasped a truth about the Church which had escaped the revolutionaries.
It was not just a plaything for cynical kings and noblemen.
It gave meaning to the lives of the poor and helpless.
For the Catholic Church, the 19th century became a great age
of devotional intensity, even expansion.
This cathedral in Boulogne was totally destroyed in the Revolution.
Now they slowly rebuilt it in the baroque style,
and they intended its dome
to be the tallest in the world after St Peter's in Rome.
And while church domes got higher, so did the claims of the papacy.
In 1814, the Pope had been swept back in triumph to Rome.
The great powers of Europe had seen that Catholicism revealed a power greater than theirs.
In spite of the Enlightenment and Revolution, the Catholic Church had re-emerged stronger than ever.
These are the Benedictine monks of St Wandrille in Normandy.
Late in the 19th century, they came back home to their monastery,
desecrated during the Revolution, the church destroyed.
But here they are, living the same life as medieval monks before them.
Except now they worship in a converted barn.
Do you feel this is a victory over the French Revolution?
I don't know if we should be talking about victories over the French Revolution, but I think it's that...
we've sort of managed to get over a trauma
that affected the Church as much as the State.
And modern France is internally divided, and I think every Frenchman in a way is internally divided,
even though they don't all realise it.
And what we've managed to get is a way of living with our past.
So a happy ending?
Almost. Almost?
Because, of course,
there's never a really definitive happy ending in this life.
MONKS CHANT
That surprising revival of monastic life showed that Catholicism wasn't just about power and wealth.
It was also about spiritual growth through humility and prayer.
Perhaps easy for monks and nuns in their stillness to see this.
But there was still a danger
that the Christian Church might accept its new triumph too easily.
Because the questions which Spinoza, Newton and Voltaire had raised had not gone away.
Catholics and Protestants alike could not avoid hearing
the insistent voices of puzzlement and conscientious doubt
and these now focused more and more on the very basis of Christian faith, the Bible.
This is the little medieval town of Tubingen in Germany.
Theologians at the famous Protestant Seminary here
set out to show the enlightened world that Christianity was true.
They were analytical. They were sceptical.
And in 1835, the work of one young man in particular,
David Friedrich Strauss, turned the eyes of all Europe to Tubingen.
Here, in what was once the University Library, Strauss wrote an audacious book,
a biography entitled The Life Of Jesus Critically Examined.
What he wanted to do was to prove that Jesus really had lived and
preached, but his Jesus was not the only begotten Son of God, was not more than a man.
And the Bible became a human creation like the plays of Shakespeare.
Its truths were the truths of Hamlet or King Lear.
That is truth, but it is not historical truth.
Strauss robbed Jesus of his divinity and denied the Bible its authority.
It was a book among many books, and the New Testament narratives
were essentially works of theological symbolism.
Without intending to, Strauss had struck at the heart of Christianity.
Strauss's ideas wrecked his career.
He was sacked from his lectureship here in Tubingen just a few weeks after his book was published.
And when he was proposed as Professor of Theology
in the University of Zurich, there were riots in the streets and they couldn't appoint him.
We shouldn't feel too sorry for him because he did get his professorial salary for life.
But by the end, he'd lost any sense of the truth of Christianity
and he found the idea of an afterlife meaningless.
I find Strauss one of the most compelling voices among those who question traditional Christianity,
because I, too, am a professor and I deal with hundreds of books every year.
If the truth of God is based on a book, and you start viewing
that book like any other, then truth is in trouble.
I, too, need to be persuaded that the Bible is different.
And that's the main reason why I can only be a candid friend of Christianity.
In less than two centuries, the truths of the Western Christian Church had been put on trial.
Newton challenged the idea of a God who intervenes in the world,
Voltaire the idea of a just God,
revolutionaries questioned the authority of the Catholic Church,
Strauss that of the Bible.
Later, Charles Darwin found evidence in the fossil record to confirm those doubts.
And yet Christianity didn't crumple.
The ideals of the Enlightenment had gradually become
the creed of respectable top-hatted historians, scientists and politicians, even bishops,
part of a cheerful Victorian belief in the steady march of progress.
And the Church still seemed to occupy the moral high ground.
It could still lay claim to one truth -
knowing right from wrong.
Mind you, in one half of the Western Church, there was a last-ditch effort
to resist the questions of the Enlightenment.
The Catholic Church felt threatened by academic challenges to the authority of the Bible.
And its reaction was just to say no.
In 1907, Pope Pius X denounced what he saw as a conspiracy to overthrow Church teaching,
and he branded it "Modernism".
Catholics unfortunate enough to be seen as a Modernist found themselves treated as enemies of the faith.
The viciousness of the official campaign against Modernism cast a long shadow across
much Catholic assessment of new directions in doctrine.
The Catholic Church felt embattled, and the 20th century gave it plenty more reasons for that,
for Pius X had missed the real, far more terrifying Modernism - the modernism of war.
The events of the 20th century upstaged the French Revolution
and unforeseen horrors unfolded which would transform society, politics and Christianity itself.
The murder of Archduke Franz Ferdinand on a Sarajevo street in June, 1914
dragged the empires of Europe into the first true World War.
The visceral experience of the Great War
began to undercut the one remaining unquestioned truth of Christianity -
its claim to moral integrity.
Men who'd been here had seen horrors that their families back home simply couldn't imagine.
It's green and quiet now. There's so much that's missing -
the mud, rats, the noise, the booming,
above all the human fear and the sense of futility at going again and again over this ground.
That's all gone.
This little book is called "Going To The Front:
"The Soldier's Daily Remembrancer",
and it was issued by the Open Air Mission of London to all soldiers.
And what it does is to try and associate Christianity, Jesus, with the English cause.
For instance, what about this for a hymn?
"Yield not to temptation, for yielding is sin
"Each victory will help you some other to win
"Fight manfully onward, dark passion subdue
"Look ever to Jesus. He'll carry you through."
It makes for chilling reading, particularly here in a place
where Christians were urged on to kill other Christians
equally reassured that God was on THEIR side.
It was hardly the first time that God had been used as a divine recruiting officer,
but it was the first global slaughter in His name.
Ten million dead in five years.
We've come here to Etaples, because this is the biggest British Empire war cemetery in France.
You've got people from India, Australia, Canada, Africa here.
There are also some Germans, and I notice that they're relegated
to the edge of the cemetery along with the native troops of the British Empire.
This is a World War and it's death on an industrial scale,
and not just death in the trenches,
because most people buried here actually died in hospital, slowly, from their wounds.
This is a wayside crucifix very near the front line.
All crucifixes show the wounds of Christ on the cross, but this has extra wounds,
bullet holes, great gashes in Christ's body.
The First World War damaged Christ's body in a wider sense.
Colonial troops were brought into a European bloodbath which had no concern for them.
And for many, the moral credibility of Western Christianity was gone for ever.
And in Europe, a generation lost its ideals, lost its optimism.
But Christianity was now confronted by a terrible challenge
which, like the French Revolution, threatened to destroy it entirely.
It also blinded many Christians to even worse moral temptation.
The threat came from another child of the Enlightenment, "scientific socialism".
In their Communist Manifesto, Karl Marx and Friedrich Engels
wrote that freedom was only possible if religion was abolished.
It was in 1917 that scientific socialism was put into action.
When the Bolsheviks seized control of the Russian Revolution and bent it to their will,
they came to see the Church as the enemy, just as the French Revolutionaries had once done.
And Russian communism had far more time to behave bestially to Christians
than the brief decade of the 1790s in France.
In those years between the wars, many Christians who feared the spread of communism
were inclined to look sympathetically on any anti-communist group.
European Christianity was drawn into a fatal alignment with forces which had little time for the God of love.
First came the papacy's deal with Benito Mussolini, finding a place for the Church in his Fascist Italy.
Then with Spain's brutal Nationalist leader General Franco,
who could present himself as the champion of the Catholic Church
as his Republican enemies burned churches and murdered priests.
GUNSHOT
But neither of these links with right-wing power was as damaging
as Christianity's entanglement with Adolf Hitler's gospel of hatred,
his project for an Aryan future, National Socialism.
It became the defining evil of the 20th century.
The Martin Luther Memorial Church, in a quiet Berlin suburb, has an uncomfortable history.
It was planned in the 1920s by conservative German nationalists
to celebrate the German identity, the legacy of Luther.
But by the time it was actually built in the 1930s,
it had been hijacked by the Nazis for their own propaganda purposes.
So the organ was first played at a Nuremberg Rally.
To begin with, Hitler wanted to bring together the Protestant state churches,
nearly all Lutheran, into a single national church based on Nazi principles.
To get his way, he appointed Ludwig Muller as the Reich's bishop.
Muller was the leader of a small group who called themselves the German Christians.
They purged Christianity of its Jewish roots more radically than any other Christian group in history.
They said that Jesus Christ could not have been a Jew.
Few versions of Christianity have openly scorned virtues like compassion or humility,
but they did.
They actually called themselves the Storm Troopers of Jesus Christ.
All the swastikas which decorated the church are gone,
chiselled out of the stone-carving and whitewashed off the ceiling.
Yet there's enough left to act as a reproach to Christian collaboration with Nazism.
But we should never forget that there WAS Christian resistance.
And for one fleeting, heartening moment it came from the papacy itself -
a pastoral letter by Pope Pius XI read from thousands of pulpits on Palm Sunday 1937.
It denounced Hitler for betraying his assurances to the Church
and condemned the idea of a Christianity that tore up its Jewish roots.
But there was little else.
And it was largely left to individual Christians in Germany
to stand up against the Nazi regime.
I went to meet a pastor who joined the new Confessing Church set up to oppose the Nazis.
He reminded me how difficult it was to stand up to the regime.
Conscientious objection was not possible.
We had one man refuse military service and got executed.
So I tried to preserve a pastoral existence as a soldier.
So what made you able to see through this nonsense when so many others could not see through it?
Hitler was betraying people in speaking in a pious way.
He said, "The providence has given me the task to liberate you,"
and many who called themselves Christians were also,
politically at least, Nazis.
They were just drunk by their idolatry and by the personality of Hitler.
It was a secular worship, and this was really...
..difficult to...
..undermine.
But it must have been obvious how dangerous it was
right from the start to be a member of the Confessing Church.
No, you mustn't read the history from the end.
We did not imagine what would be in store.
RECORDING OF HITLER
While the world ripped itself apart, one of the greatest crimes against humanity was being carried out
with ruthless efficiency across Europe.
It would leave the moral authority of the Christian Church yet further compromised
and expose a deep flaw in Christianity's historic relationship with the Jews.
This is Auschwitz-Birkenau in Poland,
the largest of Hitler's extermination camps.
It's a cemetery of one and a half million people without graves -
Poles, Romanies, homosexuals, disabled,
but overwhelmingly Jews.
Seven out of every ten Jews in Europe perished in camps like this.
It was a crime the Christian Churches failed to resist.
Average life expectancy in the camp for the men was about
five, six months, for women about three, four months.
Well, it's a grim place.
Tell me how many people would be in here.
The SS planned that about 700 prisoners
will stay in one barrack like this. Ooh.
If there were too many for the bunks, the prisoners simply stayed on the floor. Yeah.
This place is an offence against the Christian gospel.
I mean, it's an offence at an obvious level - it offends against mercy, pity, truth and love.
But on a more profound Christian level it offends
against the fact that Christianity is a story about a person, a person who is both human and divine.
This place was designed to rob human beings of their personality, to make them less than human.
It will not do to say that the Nazis were anti-Christian.
It won't even do to say that Jews died for racial reasons, not because of their religion.
The Nazis were able to do their evil, destructive work because they were so good
at playing on myths, the myths which lurk in people's minds.
And this myth was that the Jews were the killers of Christ, the enemies of Christian civilisation.
In that sense, Christianity is implicated, fatally, in the murder of the Jews.
It's hard for me, as heir to a thoughtful, tolerant Christianity in England, to face up to this.
I know that many Christians will disagree with me
and find this conclusion offensive, but here I stand, I can do no other.
In the years after the war, I was a little boy growing up in Suffolk.
I knew little of the challenges facing Christianity.
In the 1950s, church attendance actually increased in a chastened, frightened Europe.
But that mood passed.
The horrors of the first half of the 20th century had raised the old question Voltaire had posed
in response to the Lisbon earthquake.
In Auschwitz, where was a loving God?
Europe was sickened by any system which made absolute claims to truth,
communism, fascism, Christianity.
So it was hardly surprising that in the second half of the century
an unprecedented, almost frivolous, mood confronted European Christianity -
religious indifference,
apathy.
Social changes brought about a more relaxed attitude to sex and marriage,
movement between social classes and more individual choice.
In the face of that, fewer people chose to spend Sunday in church.
So what sort of Christianity could survive such an ebbing-away of Christendom?
On the edge of Trafalgar Square stands an Anglican parish church.
It tells me a lot about what's happened to Christianity in the last few decades.
On the face of it, St Martin-in-the-Fields is a church of the establishment -
the parish church for the Royal Family, the Admiralty and Ten Downing Street.
But that's not why it's internationally renowned.
St Martin's has broken new ground in exploring what it might mean to be a church in a secular, sceptical age.
Historically, it's never shied away from the controversy.
So, between the two world wars, it was pacifism.
Amnesty International was thought up in one of these pews.
Since the war, St Martin's has run its own social care unit for the homeless,
and Shelter, the charity for the homeless, was founded from its basement.
It is, in fact, a church which has taken its own lead on the moral questions
which shaped the last half-century.
There's no question we're part of the British establishment,
and we're quite good at being subversive and undermining it, too.
We're next door to South Africa House,
and from the late 1950s onwards,
the anti-apartheid vigil outside South Africa House
was supported from here,
and it's difficult to remember how controversial that used to be.
But if we think back to Mrs Thatcher talking of Nelson Mandela as a terrorist, even in the 1980s,
we begin to get the feel for that.
What we hope is that we have the courage to break new ground
and that what mistakes we make are made in the right direction.
I think the biggest test facing the Church in the last half century
has been the revolution in understanding gender, sex and sexuality.
It's the issue which really has crystallised the three centuries of debate since Spinoza.
How do we humans make moral decisions?
Where do we find the authority to make them?
It's something which I've thought about a good deal,
being a gay man in the middle of the Church's struggles about sex.
What is it about gender and sexuality?
What is it about this issue which has created so much anger and conflict?
I think you'd have to say that this is being worked out, not just in the Church, but in the world.
And the length of debate that that's taken
from the decriminalising of homosexuality, the equalising of the age of consent.
There's been a process which, actually, the Church has not been comfortable with.
And the difficulty for us is, I think, the scriptures don't say anything
about faithful, same-sex relationships and, therefore,
what's condemned in scripture isn't what we're dealing with now.
You're actually saying something quite shocking - the Bible doesn't have an answer to a major question.
I think the Bible does have an answer.
That's not the same thing at all.
I think the Bible's answer is that what matters between human beings
is loving, faithful, honest relationships.
St Martin-in-the-Fields is just one example of how Protestant Christians in the West
have tried to rebuild Christian morality with realism and humility.
Of course, theirs is not the only answer.
Other churches in central London are packed out because they proclaim
an evangelical version of Protestant faith, affirming old truths.
And then there is the other half of the Western Church - the Church of the Pope in Rome.
The big Catholic event of the 20th century
was the Second Vatican Council, which Pope John XXIII,
summoned to Rome quite unexpectedly in 1962.
Vatican II turned worship from Latin into the languages of the people.
It reached out to Protestant and Orthodox fellow Christians,
but it also apologised to Jews for nearly two millennia of Christian anti-Semitism.
And in a break from the past, Vatican II suggested that the Church
might not have all the answers, after all.
30 years ago, it seemed to set the future for Roman Catholicism,
a spiral of change, an experiment in faith.
But in 1978, a Polish bishop became Pope John Paul II.
At Vatican II, he had consistently voted against all the major decisions.
Ever since, there's been a struggle going on for the soul of the Catholic Church.
The instinct of the papacy has been to issue commands from the top,
to reaffirm old certainties in a changing world.
Catholics, as much as Protestants, are divided about the questions
which Spinoza first asked three centuries ago.
In this series, I've chronicled the history of a faith which began with a little-known Jewish sect
and exploded into the biggest religion in the world.
The history of Christianity has been the never-ending rebirth
of a meeting with Jesus Christ, the resurrected Son of God.
For some, like the Oriental and Orthodox Churches,
the meeting has been through ritual, tradition or the inner life of the mystic.
For Western Catholics, through obedience to the Church.
For the Protestant Churches, through the Bible.
And it's the variety which is so remarkable in Christianity's journey.
It's reached into every continent and adapted to new cultures.
That's the hallmark of a world religion.
So where is Christianity going in the 21st century? What's its future?
Well, it depends where you look.
In my journeys around Asia, Africa and Latin America,
I've been struck by the sheer exuberance of Christian life.
The Pentecostals, in particular, I think may surprise us.
And in fact, they may surprise themselves by what they find in their own Christian adventure.
Outside Europe, numbers of Christians are rising at a phenomenal pace,
but in the West, they are falling.
So what of the Church here, in the Christian continent which first discovered doubt?
Has the Church served its purpose here on the River Thames?
Well, when I was young, the Thames in London was a dead river -
no fish, the docks closed and mouldering, no life.
And look at it now.
If the history of the Church teaches us anything,
it's that it has an exceptional knack for reinventing itself in the face of fresh dangers.
The modern world has plenty to throw at the Church -
scepticism, freedom, choice.
But modernity can't escape the oldest questions at the heart of the messy business of being human -
questions of right and wrong, purpose and meaning.
A wise old Dominican friar once reminded me of the words of St Thomas Aquinas.
"God is not the answer, he is the question."
And as long as the Church goes on trying to ask the question, it will never die.
Remember that Christianity is a very young religion.
It spans a mere 2,000 years out of 150,000 years of human history.
It would be very surprising if it had already revealed all its secrets.
We'll wait and see, and that's just what Christians have been doing
ever since they gathered as the sky turned black in Jerusalem, at the foot of the cross on Golgotha.
Why not take part in the Open University's online survey,
"What does it mean to be a Christian today?" at...
And follow the links.
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