PHILIP PULLMAN found himself being stared at in Marks & Spencer last month. The starer was not, as it could easily have been, one of the thousands of young fans who obsess over Pullman’s His Dark Materials trilogy, but a middle-aged polemicist for The Mail on Sunday who had not long before labelled him “the most dangerous author in Britain” for telling the nation’s children that God was dead, and in this week’s Spectator has done so again.

“So I went up and said ‘Peter Hitchens?’ He said ‘Yes’. I shook his hand and said ‘Happy Christmas’. He said ‘I didn’t think you believed in all that’, and stomped off. He’s such a grump.”

Pullman does not exactly recount this story with pride (that would suggest that he considered Hitchens’s intellect serious opposition to his own), but it does not displease him either. Like the Whitbread Book of the Year prize he won last year and this month’s Radio 4 serialisation of His Dark Materials, starring Terence Stamp and Emma Fielding, Hitchens’s attack represented fame at last — and, when you are a schoolmasterly 56-year-old and your other novels have rarely done better than so-so, the “at last” is as important as the fame.

“I knew what it was like not to be a success,” he says. “I knew what it was like to write with no reaction at all. It’s like throwing a stone into a swamp. It disappears. But I suppose if you throw enough stones into a swamp, they build up a solid platform under the surface and eventually you throw a stone and it doesn’t disappear but sits there. So success came at the right time for me. I was old and cynical enough not to be taken in by it.”

Next will come the National Theatre’s two-play adaptation of the books, after that a film from a Tom Stoppard screenplay. It is surely only a matter of time before the must-have Christmas toy is an alethiometer (his heroine’s fortune-telling compass), available from all good toyshops at £39.99, until they sell out in late October. He says he doubts it, but if so, he’ll make sure he gets his royalties.

Success has already bought him a new home in a village a few miles from Oxford, the city that dominates His Dark Materials as it has his adult life.

After studying English at Exeter College, he spent most of his teaching career in Oxford middle schools. He no longer writes in a garden shed but in a large, rather exotic study, where he stands at a keyboard next to the old shed’s window, which has been artfully decorated with a montage of wallpaper and Post-it Notes from the old den’s walls. Success is relative, however: having looked at Ian McEwan’s old house in north Oxford and its £1.25 million asking price, Pullman and his wife, Jude, passed. He is not yet J.K. Rowling (or Ian McEwan).

After a lunch in, during which he reveals an appetite for uncharitable gossip about clergymen, I begin quizzing on spiritual matters. I find him a lot more certain and pontifical than the former Bishop of Durham, whom I have happened to interview the day before. Happily, his replies are mocked by sonorous snoring from his pug, Hogarth, who’s a-snooze on his lap.

I confess some sympathy with Hitchens’s confusion about Pullman’s beliefs. His Dark Materials is a paradoxical, an atheistic, saga about God. In a fantasy universe such as it occupies, there is nothing too troubling about witches, talking bears or pixies, although I personally find a little goes a long way. Pullman, incidentally, also prefers realist fiction and admits to feeling “slightly shifty” that it is not until he writes fantastically that his plots take flight.

What is problematic for those who fall on the trilogy as an antidote to C.S. Lewis’s beguilingly godly The Chronicles of Narnia is that Pullman’s cast also features the Genesis dramatis personae. In mitigation, the angels seem to be homosexual, human souls manifest themselves as animals or “daemons” and God, when he finally turns up, is senile, but the cast is still all there. The Catholic Herald condemned the books as worthy of the bonfire for their atheism, if not their satanic tendencies. My feeling is that, although they are anti-Church, they are not nearly atheist enough. His Dark Materials assaults the Judaeo-Christian creation myth, but only by supplanting it with a myth of its own.

It turns out that his rival Book of Genesis actually exists, Pullman having jotted it down over eight pages when he started off ten years ago to ensure that the novels’ “scenery did not wobble”.

“God came into being,” he explains. “He was not the creator, but He was the first. And when other beings arose, the first angels, He told them that He was the creator and they worshipped Him and obeyed Him because He told them to.

“One of them was the Sophia — this is where I use previous mythology, gnosticism and the idea of the Sophia, the wisdom — and she advised the being that called Himself God, not to do this. Don’t rule in this despotic, tyrannical way. Let us all respect one another. Let us all be equal.