Throughout the intertestimental period, and up to the middle of the third or fourth century, Jews actively sought out converts–which put them on a collision course with the rival synagogue of the Christians. Most of the patristic broadsides against “Judaizing” (e.g., that of John Chrysostom) can best be understood in that context. Even the crushing defeat of Bar Kochba’s rebellion (AD 135), which ended Jewish apocalyptic pretensions, did not end Jewish proselytization. As late as the 8th century, the Turkic Khazars adopted Judaism en masse, and were accepted as Jews by the rabbinate in Persia, the Middle East and Europe.

The exclusivist, or at least highly restrictionist attitude of modern orthodox Judaism is probably a reaction to the Christian and Muslim oppression of the Jews from the Middle Ages onward. With the conversion of both Christians and Muslims a legal offense with highly adverse effects for the Jewish community as a whole, it was natural for the rabbinate to make conversion as difficult as possible, if not outright impossible. The advent of religious liberty in the post-Enlightenment West created new opportunities to attract converts (the up-side of intermarriage), but in the Middle East, conversion remains a politically and socially charged issue.

Modern Jews will have trouble addressing the conversion issue effectively until they are willing to examine their entire history, to understand how their present attitudes evolved, and whether they have a real Talmudic basis, or were merely a transient response to historical conditions.