Jewish Attitudes Toward Proselytes
At times, Jews have embraced large numbers of converts, but hostile relations with Gentile neighbors often led to suspicion of proselytes as well.?http://www.myjewishlearning.com/beliefs/Issues/Jews_and_Non-Jews/Attitudes_Toward_Non-Jews/Converts.shtml
Those Gentiles who were members of Israelite society were known as gerim (strangers or foreigners), and the Bible repeatedly emphasizes the obligation to welcome such people.
Jews in biblical times were open to prospective proselytes, but they did not see it as their mission to convert Gentiles. [Not sure the author is right.]
The most famous negative statement in the Talmud about converts was made by Rabbi Helbo, who believed proselytes were "as troublesome as a sore." Most sages appear to have disagreed with Helbo, however, and tried to list specific historical circumstances which led him to this conclusion. Most prominent among these was the fact that the proselyte and his new Jewish community often suffered punishment from Christian leaders following a conversion.
The Middle Ages
...On the other hand, the Zohar (the classic work of kabbalah, medieval Jewish mysticism) strikes a different chord. The Zohar emphasizes the superior position of the born Jew in relation to the proselyte.
?]This theme probably reflects the extent to which Jews felt persecuted and, consequently, entirely separate from the Gentile majority.
Today's "Jews by choice" are in large part accepted by American Jewry. Most Jews consider them a welcome addition to a community struggling to ensure its own survival in future generations. Yet even as they might fully accept proselytes as co-religionists, American Jews often feel that Jews-by-choice cannot fully share the bond of Jewish ethnicity, peoplehood, or history--at least not immediately. The contemporary situation is especially complex in Israel, where only conversions performed by Orthodox rabbis are regarded as legitimate.
The author seems to say that in Old Testament times it wasn't this way.
So, is this looking down on non-ethnic Jews as spiritually inferior just something from Zohar and somehow a reaction to Christian persecution?