Giles Fraser: Doubters do it from the pulpit

'I may be wrong' is not a phrase one ever associates with Richard Dawkins

Perhaps it's time for a new sort of conversation about religion. The old one is getting really very tired, as in some overblown boxing match between two bruisers who just won't topple. They slug it out. Land huge blows. Declare victory. Only for the opponent to rise again (no resurrection reference intended) and for the whole sorry circus to wind itself up for a rematch. Top of the bill: Richard Dawkins vs Osama Bin Laden. Or A C Grayling vs some nutter from Christian Voice. Whether it's over wearing crosses or the niqab, the role of faith in education, or the moral status of the unborn child, binary opposites are regularly set up as the fight of the century by some unimaginative media impresario hoping to engage an increasingly indifferent crowd.

Actually, that's not altogether fair on Professor Grayling. For over the past few months he has been involved in a really interesting project, co-writing a play rather abruptly titled On Religion. It's not that Grayling has lost any of his atheistic bite, but in writing a piece of theatrical drama he has had the savvy to recognise that humanist propaganda might not make for the most riveting theatre. And so, the famous media atheist has been obliged to enter into the imagination of the religious in order to produce a convincing portrait of what it is to believe in God.

I ought to declare an interest here. The religious character in the play is roughly based on a series of interviews I gave in various pubs in south London. Of course, I began the project with the distinct anxiety that my faith might be misrepresented by two atheist authors. After all, I am a failed atheist myself and nobody likes a turncoat. And while my position comes in for a bit of a kicking, it is not misrepresented. It is allowed to speak in its true voice. And that, perhaps, offers hope for a new sort of conversation.

But something more is needed. For a more interesting discourse about religion would also have to involve the reclamation of agnosticism, of the ability simply to admit that one doesn't know. In the preface to Richard Dawkins's new Christmas stocking filler The God Delusion, he thanks his wife "who has coaxed me though all my hesitations and self-doubts". But it cannot have been too difficult a job, for this is a book so lacking in self-doubt that it's positively evangelical in the confidence of its self-belief. "I may be wrong" is not a sentence one could ever associate with Dawkins. And his work is so much the poorer for that.

The other evening a few hundred people gathered in St Mary's Church, Putney, south-west London, to model a conversation beyond the lust for certainty. On the platform an atheist, a priest, an ex-priest, a scientist and a philosopher. And all agreed on one thing: that public discourse about science and religion has been overly dominated by those who claim too much conviction for their own position. As if the admission of uncertainty is some sort of moral weakness in the great battle over faith.

Christian agnosticism, in particular, is easily caricatured as a marginal activity for the overly philosophical or theologically timid. In fact, only those already lost to the lust for certainty, or those who had never read a word of the Bible, could come to this conclusion. For the Bible constantly refuses to give God a definite shape and size. That's what the Hebrew Scriptures call idolatry and what Marxists, following on, came to call reification. It's turning God into a golden calf. Kant was right when he argued in the Critique of Judgement that it is the second commandment, the refusal to allow human beings a fixed view of God, which offers the most significant protection against religious fanaticism. The idea that God is essentially mysterious may not cut much ice with atheists, but it is much more threatening to fundamentalists.

And it's not just Jewish theology that makes this move. The Christian doctrine of the Trinity is far from being a peculiar sum in which, (on the basic of a dodgy sleight of hand concerning some three-leafed clover) apparently, 1+1+1 adds up to 1. Quite the reverse: it's a form of Christian agnosticism that refuses a clear and settled account of God. The Trinity is a theological vaccination against reification. The triune God can never become a thing because the logic of the trinity will always pull it apart. God is not to be captured by the human imagination. Which is to say that Christian agnosticism is not a half-faith for those who cling to belief with their fingertips. Historically, this is the true orthodoxy. And those who work out their faith in a certain doubt and confusion are, in fact, the true believers. Walking by faith and not by sight, as St Paul puts it.

Some atheists are threatened by non-fundamentalist faith. They reckon it a liberal alibi for fundamentalism, offering a more superficially plausible account of God which serves only to shelter fanatics from the sort of criticism that would put them out of business. On this reasoning, atheists have a vested interest in presenting the worst sort of faith as the real thing, thus enabling the whole sorry lot to be all the more easily ridiculed. This is Dawkins's strategy.

A contrasting approach would be to work on the assumption that the most effective way to attack bad religion is with an alliance that includes good religion. And thus it's in the interests of all - including non-believers - for religion to be allowed to present itself in the best possible way. Fundamentalists have become such a threat to us all that a new deal is required between progressives, religious and non-religious. The discussions that went into On Religion demonstrate that it's not as hard as it seems. The old debate must change.

Giles Fraser lectures in philosophy at Wadham College, Oxford, and is vicar of St Mary's, Putney