BOOK REVIEW / Among the ghosts of the future: 'The God-Fearer' - Dan Jacobson: Bloomsbury, 13.99 pounds

What if . . . ? What if Judaism rather than Christianity had been the principal, state-linked religion of Europe? Would the faith have changed? Would history look very different? Would our sorry past lack its spectres of scapegoating and persecution?

Kobus, Dan Jacobson's elderly hero (or anti-hero) is a God-fearer, a member of the dominant group whose beliefs derive from the ancient Yehudim. He is a retired printer and bookmaker and his trade is important, since people trust in the word, the 'message', the official document, the learned tome. Looked after by his servant Elisabet, he is alone in his house until two mysterious children appear, a girl and a boy, playing silently, dressed in the garb of the Christers, the despised Jesus-sect. Kobus begins to doubt his sanity: at 84, having suffered a stroke, his mind is confused, as when he remembers - or tellingly misremembers - the story of the Furies or 'Kindly Ones', an old Yavanit myth.

What he does recall is his own pursuing youth. The phantom girl is Sannie, a Christer servant whom he had known as an apprentice and tentatively desired. In a Salem-like outbreak, fuelled by a tormented believer whom Kobus himself had unwittingly driven into lunacy by his questioning of God, Sannie was denounced as a witch. When Kobus was called as a witness on her behalf, he had turned his back.

The place and time are unspecified, a stage-set Middle Europe slyly suggestive of the 16th century, or, indeed, of fairy-tales: twisted chimney-pots and cobbled alleys, wooden clogs and lace caps, towns 'a hundred leagues' apart. Jacobson has clearly enjoyed inventing a different world order, where the God-fearers hold power and inhabit the town-centres while the wretched Christers cluster in hovels on the outskirts, practising their 'grotesque', God-eating rituals. At one point Kobus plays at historical inversion himself, indulging the 'mad fantasy' that it was Christ that the later 'Romait' empire embraced, and that the God-fearers were the outlaws: 'Another history] Another past for half the human race . . . Another imagining.'

Yet both versions are ultimately the same. The accusations of pacts with the devil may have vanished, but the vengeful turning on the powerless has certainly not. The riots, violence, fires, deaths and tyranny which accompany this novel's 'Ten Turmoils' stretch through European history from the Middle Ages to the Holocaust and to today. Kobus is too intelligent to think he could have changed the course of history, or even the verdict at Sannie's trial, but that knowledge does not absolve him.

What could have been a bleak, schematic moral fable is brought to life by Jacobson's sympathetic imagination and tender, deceptively direct narration, which moves easily from the concrete - 'Picture Sannie in this setting; 15 years old; clothed in a grey, checked dress of coarse cloth; her legs bare . . .' - to Kafkaesque visions of a swarming, fear-driven field full of folk, desperate to prove their identity to faceless officials armed with indecipherable scrolls. The ghost story, a genre of 'non-existence', suits his speculations, which ask us to deny history as well as suspend disbelief. His accusing, appealing revenants are innocents, the ghosts of Kobus's past and also of the future that his actions have denied, and the self that he has sacrificed; his partial atonement is a final, disordered account of the 'truth', for posterity to learn from - perhaps.

The God-Fearer is a beautifully restrained, haunted, humane fiction: 'To each of us his own obsession. To each his expected visitants.'