a few centuries after the rabbis began their work, the Roman Empire adopted Christianity as its official religion. This huge transformation did not occur overnight, but nevertheless it was shocking. The Jews had been one ethno-religious group among a great many, each worshiping its own collection of divinities (of course, the Jews' “collection” was smaller than the others); now everyone worshiped the same God (in fact, they said it was the Jewish God!), and the Jews alone remained outside the new consensus. Over the fourth and fifth centuries, the evermore powerful Church put an end to all other forms of worship, the ancient religions of Greece and of imperial Rome itself among them: only Judaism remained. A religion claiming to be the very fulfillment of Judaism had swept the world, and only the Jews themselves refused to acknowledge its claims. The people of Israel had become the only non-Christian minority in a newly Christian world.

To understand the background of this development, it is necessary to look back to the beginnings of Christianity. If Christianity began as a movement among Jewish followers of Jesus, how did it become a religion in its own right, with a largely non-Jewish membership? This development, wholly unexpected from the Jews' point of view, was largely the product of one man's teaching. At its earliest beginning, the movement was fiercely opposed by a man with the biblical name Saul, by his own description a dedicated Pharisee who could not abide the teachings or the practices associated with the followers of Jesus.