Christianity has a long, unhappy and all-too-recent track-record of anti-Semitism. It was only in 1965 that the Catholic Church forgave the Jews for deicide, having spent much of the intervening two millennia murdering and slandering God's chosen people in waves of hysteria. Yet history is clear that Christianity grew out of Judaism and since the two creeds are so alike - with a common root in the Old Testament and, on major questions, a common monotheistic theology - this must be the worst- ever case of sibling rivalry. The aggressive, vengeful younger child is unwilling even to acknowledge a family link with its older, more introspective brother.
Reminding Christians that they are, in effect, a heretical Jewish sect still has a peculiar power to unsettle. A N Wilson - novelist, ex-Anglican and unrepentant agent provocateur - spares no pious blushes in his new study of Saint Paul. Jesus was, he states bluntly, a minor "Galilean exorcist", interested in Jewish matters and one of many messiahs who 2,000 years ago attracted the attention of a people desperate for divine assistance in overthrowing their Roman overlords. The tiny cult that surrounded him after his death would soon have petered out had it not attracted the attention of Paul of Tarsus, for Wilson "a richly imaginative but confused religious genius who was able to draw out a mythological and archetypical significance from the death of a Jewish hero".
Inspired by the image of the crucified Jesus, Paul set about fashioning his own belief system. It owed little to Jesus and borrowed largely from the Greeks and other religious traditions. Paul also led the missionary push that focused the attention of the new sect away from the internecine struggles of Judaism and on to the wider possibilities of the Gentile world.
Jesus, then, was not a Christian. Paul invented Christianity and recreated Jesus's memory to aid the cause. Today's Christians are not Christians, Wilson delights in announcing, but Paulians.
His theory is stated in confrontational style but elegantly and accessibly put. By going back over Paul's own writings, current knowledge of first- century Judaism and the gospel accounts - with all their drawbacks as documents of record - he overturns the standard Christian notion, taught in Sunday school, that Paul was recruited on the road to Damascus to an already-growing Christian Church. Paul never mentions Damascus and the apostles had hitherto demonstrated little aptitude for evangelisation.
As Paul moves from foot-soldier to general in Wilson's revisionist history, other treasured items of Christian folklore tumble: Jesus was born in the city of Sepphoris in Galilee, not rural Bethlehem, the author mentions almost casually. After all, he implies, that is the orthodox view in scholarly circles and theological colleges. All he is doing is breaking the taboo and relaying the news to the great unwashed in the pews.
Fear of causing a crisis of faith in the rank-and-file has led theologians and bishops - with the exception of Durham's former incumbent David Jenkins - to keep such theories private. Wilson's expose therefore raises the question of whether he is mounting an attack on Christianity as a whole, or just readjusting the focus through which the early church and its accredited founder are viewed.
If this book is taken in conjunction with his earlier Jesus - a warts- and-all biography that examined the historical Christ and his deeds - there is a temptation to see Wilson as mirroring a personal rejection of belief in his work. Certainly, both books will appeal to an audience happy to see the church taken down a peg or two.
Yet Paul has always been a controversial character in the Christian canon. Wilson writes of himself not as a missionary atheist who wants to know how the Christian story ends, but as one who "after 20 years of thinking about it, can not really decide even the rather simple question of how it begins". Like Wilson's very public promotion of himself as an old-fogey, this book is designed to raise eyebrows, but its resounding success at translating high-minded and often opaquely phrased ecclesiastical debate into a popular format should be applauded, not feared.