What is religion for? The Archbishop of Canterbury offered some ideas during his recent tour of Zimbabwe, when he challenged President Mugabe over the persecution of Anglicans there: it is about telling truth to power, whatever the consequences, he indicated, about the meek inheriting the earth, about justice.

Then this week the people who run St Paul's Cathedral gave us a lesson in what it's not for.

We are at a strange moment in history when materialism appears to have run its course. With the Industrial Revolution, material accumulation became our true religion. Karl Marx merely refined the creed, vowing to make Mammon worship man rather than the other way around.

But in the past 20 years these gods have failed, one after another. The anti-City protesters outside St Paul's were not there as penitents or pilgrims, nor even as believers, yet the symbolism was strong and valid. Here in the heart of capitalism was a great symbol of the spiritual world, the dome which rode out the Blitz. Amid the gleaming, depopulated streets of the City, here was another truth, a different realm of values. It was right and just that the protesters should muster there, and that the cathedral should make them welcome, or at least let them be.

Then they locked the doors – for all those excellent modern reasons we are familiar with.

On Saturday the Canon Chancellor of St Paul's fiercely rejected the notion that the building had been closed on commercial grounds. That was to miss the point. Nothing could be more symbolic than for the building to permit the protesters to stay, to forge a partnership with them, to remain open to them and to anybody else. Nothing could be more bleakly symbolic than for it to wash its hands and turn away.

In Harare, before 15,000 Africans packed into a stadium, Archbishop Williams said, "You know very well, dear brothers and sisters, what it means to have doors locked in your faces by those who claim the names of Christians and Anglicans. But... the Lord proclaims that he has set before us an open door that no-one can shut. It is the door of his promise, the door of his mercy, and the door into the feast of his kingdom."

The protesters outside St Paul's are demanding an end to the reign of naked greed over our lives. It is a proposal in which one would expect Christians of conviction to play an active part. By turning them away, St Paul's has indicated that, whatever the church's spiritual message, for those who run the place its fabric is more important. That's a bureaucratic way of saying, yes, God is dead.

p.popham@independent.co.uk