Although the early Christian movement spread rapidly beyond the boundaries of the Jewish homeland, it did not thereby lose its intimate relationship with the Jewish nation. There were many more Jews living outside Judaea and Galilee than within their borders, and the long-established Jewish networks of contact and communication were the best conduits through which the new messianic movement could travel. As the Christian message began to spread to the Greek coastal cities (Joppa, Caesarea, Tyre, Sidon) and the large urban centres to the north (Damascus, Antioch), it was in and through the synagogues that it made its impact (Acts 8–10). Indeed, there is evidence to suggest the prior presence of Jews in almost every location where we can trace the spread of Christianity in its first two centuries.

As we shall see, the character of the relationship between the fledgling churches and the established synagogues was variable. The Jewish communities in the Diaspora were usually the initial home of the early Christian groups, but often subsequently their chief competitor. In either capacity they provided a model for the communal life of the first Christians and unwittingly contributed the literary and intellectual resources with which Christianity constructed its own identity. Thus, directly or indirectly, the Jewish Diaspora influenced the development of early Christianity to a very significant degree.