As long as believers in Jesus were a Jewish group, the rabbis maintained an ambivalent attitude toward them. But as soon as the majority of Christians were Gentiles who had not converted to Judaism, they were no longer a sect but a separate religion.
I have no issue with this. I think, however, that early Christians saw themselves as, for a lack of a better conceptual term, better Jews. The Rabbis no doubt did exclude the Gentile-sect of Judaism; however, the early sect, even post-Bar Kokhba, most likely still viewed themselves as Jews, or rather, still in the Jewish religion. Matthew’s Gospel, after all, is about continuity between Jewish-Christians and Jewish-non-Christians after the destruction of the Temple. I would argue that Ephesians is an argument to Jewish-Christians from Jewish-Christians to include more Gentiles into the community after the destruction of the Temple.
I’ve maintained that 2 Peter is best dated to the early to mid-second century given the closeness 2 Peter 1.15 and Irenaeus’ description of Peter and Paul’s death. Note that in this letter, the same letter mentioning Peter’s “soon” death, Paul is likewise mentioned indicating how successful these two had become as identifiers of the new sect. I have to wonder what a reading of 2 Peter as a reaction against the religious aftermath of the Bar Kokbha revolt would reveal. Clearly, the author here is railing against false teachers who deny the Gospels, Jesus as Messiah, and I would also argue against Peter but so too, and more importantly, against Paul who would have been read as a diatribe against (an)Judaism. I believe we can see this in 2 Peter 2 when the author picks up some of the similar, albeit less eloquent, arguments from Galatians. I think reading 2 Peter post-Bar Kokhba not only fits the time frame but will yield textual evidence to the expected response (from (an)Christians) from Dr. Schiffman’s view.
I do think that the revolt in the 130’s caused a major separation. Dr. Schiffman’s statement recording the end of the Jerusalem Jewish-Christian church is something of a recorded event and would explain many things.
As a side note, my recent paper at SBL has been proven well by this series of exchanges, to which I am grateful to Dr. Schiffman.