It is said that popular culture is becoming increasingly infantilising. JK Rowling made it acceptable for adults to sit on the train reading a book about magical boarding schools, infused with the nostalgia of books from our own childhoods (Anthony Buckeridge’s Jennings, Susan Cooper’s The Dark is Rising), but the process was already well underway when Hedwig and Hagrid were first put to paper. As the average age of the cinema-goer decreases, so the market-enslaved Hollywood studios grind the common denominator of characters, themes and jokes lower with each summer season. Films for the very young are the exception, since filmmakers must cater to both their ostensible audience and the parents who accompany them. I remember the songs in their soundtracks from my own youth, and the cultural references and allusions are often, sadly, more diverse and engaging than in films supposedly for grown-ups.

It is not a happy state of affairs. And parenthood tends to make one resent this trend even more; if I am to escape Pokémon and Dinosaur King, the last thing I want to read or to watch is a rehashed ‘kidult’ coming-of-age story. There are some notable exceptions. Neil Gaiman is one, with his inexhaustible imaginative scope. For me, the standout is Philip Pullman, whose books manage to engage with big ideas in the midst of compelling, fast-paced stories. They are written for older children but they transcend age in a way that is claimed (rarely deservedly) of other books. I have tried several times to get my eldest daughter to read Northern Lights, but she wasn’t quite old enough, and I think the lumbering film adaptation of The Golden Compass might have put her off, understandably, so I’ve taken to leaving The Ruby in the Smoke lying around at strategic points where she might idly pick it up.

Tomorrow, Pullman’s latest book, The Good Man Jesus and the Scoundrel Christ, will be launched by Canongate. It’s an adult book this time, with the premise that Jesus of Nazareth had an evil twin named Christ. From the excerpts published in the Guardian last Saturday, it has some of the ring of the Gospels about it, but it’s also instantly recognisable as Pullman’s thoughtful, compassionate prose. Here’s Christ having a rather wistful post-coital chat with a prostitute about his twin, Jesus:

“Do you want to be like him?”

“More than anything. He does things out of passion, and I do them out of calculation. I can see further than he can; I can see the consequences of things he doesn’t think twice about. But he acts with the whole of himself at every moment, and I’m always holding something back out of caution, or prudence, or because I want to watch and record rather than participate.”

There will be the predictable howls of outrage from the religious right. More interesting will be the reaction from intelligent theologians such as Rowan Williams, the Archbishop of Canterbury – according to Pullman, it was during a debate with Williams (transcript available on the Telegraph’s website, well worth reading in full) that he first came up with the idea for the book:

In the course of talking about His Dark Materials, he said that he was curious to know why, although the story was plainly about a form of the Christian church, there was nothing about Jesus in the book.

I said that he was right, there wasn’t, and that I’d deal with Jesus later in another book.

I will have to reserve judgement until the book is published, but if the excerpts are any guide, it will be a more nuanced contribution to the current debates over religion, humanism, the Christian faith and atheism than the vulgar broadsides of Dawkins et al. I wonder what Slavoj Žižek (who despite being a materialist philosopher and atheist, has theorised on the radical implications of Christian theology) would make of Pullman’s Jesus/Christ dualism?