It is an occupational hazard for anyone who thinks deeply about Jesus and his message that they can end up with a portrait that looks uncannily like themselves.
High churchmen, for example, uphold Jesus as a great high priest. An American advertising executive praises him as the great advertiser of his day, expert in taking his message to the contemporary marketplace.
For English philosopher Don Cupitt, he was a secular moral teacher and a pioneer of radical humanism in ethics.
A century ago, Catholic modernist priest George Tyrrell noted the same phenomenon when he wrote a critique of a German scholar's attempt to distil the essence of Christianity.
He famously concluded: "The Christ that Harnack sees, looking back through nineteen centuries of Catholic darkness, is only the reflection of a Liberal Protestant face, seen at the bottom of a deep well."
The modernists were trying to open Catholic thinking to new understandings of the world and the Church. Pope Pius X responded by excommunicating them.
That kind of authoritarian repression is anathema to English novelist Philip Pullman, and it is hardly surprising that as he stares down his own well, he sees a Jesus disillusioned with God and rejecting the Church - though in Jesus' day, of course, the Church had yet to emerge.
Pullman's latest book, The Good Man Jesus and the Scoundrel Christ, retells the central gospel stories with an underlying sceptical bias, though sympathy occasionally shows through.
Recent scholarship prises apart the human Jesus and the Christ figure long identified with him: Pullman adds a novel twist by making them twin brothers - but only to emphasise how different they were.
His Jesus is sturdy, passionate, and wholly focused on his vision of making the kingdom of God a reality in the here and now. His Christ is sickly, introspective and controlled, an observer rather than participant in what Jesus is doing.
He continually calculates what will be needed to project Jesus' message into the future. He knows miracles will help, but his brainwave is to create a Church - and you can sense Pullman's hackles rising.
That solution becomes one of the three temptations which Christ, substituting for Satan, puts to Jesus in the desert. Create an organisation, he says. Give it one supreme director, and watch its influence spread. See the Church sweep away dissent and bring about God's kingdom on Earth.
"You phantom," retorts Jesus, who has already branded his twin a scoundrel for suggesting he turn stones into bread. "What you describe sounds like the work of Satan." That's vintage Pullman, gazing down his well.
A similar fanciful distortion is Christ's taking the place of Judas in betraying Jesus. Another is Jesus' total estrangement from God on the night of his arrest, finding God silent, blind and deaf.
After the crucifixion Jesus stays dead, but in the half-light of Easter morning, his twin is mistaken for him. Christ does not correct the impression.
He then helps to embroider the emerging record of what has gone before - for no other reason, Pullman tells us, than to make a better story.
Then, having done all he could to carry Jesus' message forward, Christ marries, settles down in a coastal town, and spins out his retirement making nets.
Ironies abound. Despite his scepticism, Pullman is obviously drawn to Christianity's central story, which he concedes elsewhere is essential for anyone wishing to understand Western civilisation.
Though critical of the way the gospel writers added to, edited and interpreted the story of Jesus (his word is manipulated), he is not averse to manipulating it even more to serve his own ends.
Similar atheistic crusaders have written books denouncing all the Church stands for, usually without any real understanding of its breadth and depth. Quite against their intent, however, they all do religion a service by keeping the discussion of faith alive in the secular marketplace, where the Churches cut no ice.
Also, it is the Church they deplore that has kept the memory of Jesus alive, despite the many bad things it has done alongside so much good. That memory is pivotal. Not only does it provide Pullman with a subject worthy of his literary talent: it also continually judges, corrects and renews the Church itself.
A pity, then, that this fable of Christian origins is so often wayward, and theological folderol. As for Jesus' rejection of God and of the Church created in his name, that is only the reflection of an atheist's face, seen at the bottom of a deep well.
- Ian Harris is a journalist and commentator
