John, By Niall Williams

New Testament scholars, in search of the historical Jesus via Matthew, Mark, Luke and John's accounts of his life, death and resurrection, have long and dryly debated who precisely was the author of the fourth gospel.

Was this John the same John who wrote the Book of Revelation, the final and terrifying chapter of the New Testament? Or was he the Apostle John, called Jesus's "beloved disciple", to whom he entrusted the care of his mother as he died on the cross? Or both?

The scholars go round and round in circles. Their failure to provide clear answers is, I suppose, in the very nature of the relationship between the gospels and history. But then along comes Niall Williams, author of Four Letters of Love, who, momentarily and majestically, makes all that scholarship redundant with his sixth novel, John. Neither history nor biography, it is above all the work of an extraordinary imagination based on the simplest of questions, revealed by Williams in his afterword, namely: what was John doing the day before he wrote his gospel?

Answering it has led him to fashion a moving portrait of a man of courage and faith in trying times. The story is, of course, rooted in the Christian tradition, but its power and insights do not rely on readers having any interest in the Church. So John waits, blind and inwardly bemused, in exile on the island of Patmos, anticipating the imminent promised Second Coming of Christ. Take it as a metaphor for whatever you choose. He has his doubts, but a whole community gathered round him depends on him to remain strong and fix them on the forthcoming Day of Judgement. And so, as publicly unmoveable as the rocks of which barren Patmos is made, he does precisely that.

Only his young disciple Papias senses his inner turmoil – and experiences his own. Doubt is laid on doubt when one section of the Patmos community, led by Matthias the chancer, embraces a new creed that makes its prime advocate "the chosen one". The rebels leave Patmos with their saviour, seemingly lost forever, but then John's exile is ended by the death of the Roman emperor, and he and his dwindling band follow them to Ephesus where their two approaches battle it out in a hostile environment.

The actual events of the novel are slight, and to anyone who knows their Bible will be all too predict-able. But no matter. What beguiles about John is the power and poetry of Williams's language, deployed in such a way as to take out of its particular context his subject matter and endow it with a universal significance. John's habitual self-sacrifice, almost but not quite to the point of self-abnegation, is contrasted with the egos of those near him – from the smooth-talking Matthias, right through to the faithful Papias, tempted by a damsel in distress, sufficiently arrogant, even in his essential humility, to think that he alone can save her.

There is something terribly old-fashioned about this novel as it foregoes plot, pace and everything supposedly guaranteed to draw in the modern reader. Yet it still demands to be read in one sitting.

Peter Stanford's latest book is 'Teach Yourself Catholicism'