The Jess who fled the wars against the Romans and who’s this avoided the enslavement that came to (a million) ended up in places like Alexandria and Toledo as well as in Mesopotamia. Furthermore, the Jews, unlike Christians, had legal status among the Romans. I don’t think we gained such status until the time of Constantine. After which, it seems, many ‘Jewish”people became Christians for the same reason that pagans became Christian: out of conviction and out of expedience. Same thing happened in Spain in the 15th Century. I think in both instances, “old Christians” resented the Jewish converts, and when the Jews used their talents to prosper, this led to suspicion and even persecution. The Jews were expelled from Spain and the Inquisition devoted itself to ferreting out “secret Jews,” as they later would “secret Muslims”. Ironically, a large number of Spaniards have Jewish blood, and the Inquisition sees to have got rich by issuing statements of “purity.”to well-to-do families. St. Teresa had Jewish ancestors, which is one reason why she was brought to the attention of the Inquisition. One of the great tragedies of history is the way that Jews and Christians have been at each others’ throats since the beginning. Another thing that's often overlooked is the series of Jewish revolutions against Rome in the 1st and 2nd centuries. Jews became outcasts because of their insubordination. It became dangerous to appear that you were doing anything "Jewish". Though it's pretty clear that all early Christian observed the holy days of Leviticus 23 (including the weekly sabbath) and the food laws it soon became undesirable to do these thing while under the eyes of Rome. As a result many in Rome decided to adapt acceptable days...those that were currently being celebrated by pagans in Rome.
People forget about the Jewish uprising during Trajan’s time. Becauswe it involved the Jews of the diaspora, who were quite numerous, it forced the Emperor partially to withdraw from Mesopotamia before he could consolidate his victory. Timing is everything. If a similar uprising had occurred during the Palestinian uprising, Jews were so numerous that with the aid of the Persians, such as they were in the ‘60s. they might have succeeded in making the whole Levant inhospitable to the Romans. People forget that from the Maccabees onward, the Jews had shown what formidable fighters they were.