How did Judaism diffuse?

Answer 1

Judaism/Israelite Religion did not diffuse outside of the southern Levant until the Babylonian Exile period when the elite from Judea were deported to Babylon. It became a rather large community there before returning to the southern Levant under the permission of King Cyrus of Persia. During the Persian and Hellenic Greek Periods, Judaism remained a Middle Eastern religion. When the Romans exiled the Jews from Judea after the Zealot Revolts and the Bar Kochba Revolts, Jews were scattered to all of the corners of the Roman Empire.

In the post-Roman Empire period, Jews migrated from country to country whenever they were exiled or offered much better opportunities elsewhere. In this way, Jews diffused into many different European and Arab societies, as well as becoming a small part of India and China and later the New World.

Answer 2

1) Judaism diffused as the Jewish communities spread and moved. This phenomenon was set in motion by the various expulsions and persecutions, which drove Jewish populations to settle in new places.
2) As non-Jews came in contact with Jews, there was a degree of influence upon them. Ancient writers speak of large numbers of people in the Mediterranean area who had taken on various Jewish practices. It was these semi-converts who were especially likely to adopt Christianity.

3) As the new religion of Christianity spread, it taught those beliefs which it had adopted directly from Jewish sources, such as the prohibition of infanticide and human sacrifice.

See also:

The influence of Hebrew traditions on the Western world