'In the beginning was the Word,' says the Gospel of John, and this sentence - and the words of all four gospels - are central to the teachings of the Christian church. They have shaped Western art, literature and language, and the Western mind.

Yet in the years after the death of Christ there was not merely one word, nor any consensus as to who Jesus was or why he had mattered. Instead, there were many different Jesuses, among them the arrogant, aggressive Jesus who scorned his parents and killed and crippled those who opposed him, the Jesus who sold his twin into slavery and the Jesus who had someone crucified in his stead - then laughed.

Moreover, in the early years of the first millennium there were many other saviours, many sons of gods who healed the sick and cured the lame. Among them were Asclepius, the son of Apollo, who made the blind see; gentle, long-haired Apollonius, who raised the dead and Zalmoxis, who promised his followers eternal life.

But as Christianity spread across the Mediterranean, these other saviours were pronounced unacceptable - and in some cases heretical - and they faded from view. Now, in Heretic, Catherine Nixey tells their extraordinary story. It is a story of contingency, chance and plurality; it is a story about what might have been.