Council Of Jamnia
There was a slowly growing chasm between Christians and Jews, rather than a sudden split.
Even though it is commonly thought that Paul established a Gentile church, it took centuries for a complete break to manifest. However, certain events are perceived as pivotal in the growing rift between Christianity and Judaism. The Council of Jamnia circa 85 is often stated to have condemned all who claimed the Messiah had already come, and Christianity in particular. However, the formulated prayer in question (birkat ha-minim) is considered by other scholars to be unremarkable in the history of Jewish and Christian relations. There is a paucity of evidence for Jewish persecution of "heretics" in general, or Christians in particular, in the period between 70 and 135. It is probable that the condemnation of Jamnia included many groups, of which the Christians were but one, and did not necessarily mean excommunication. That some of the later church fathers only recommended against synagogue attendance makes it improbable that an anti-Christian prayer was a common part of the synagogue liturgy. Jewish Christians continued to worship in synagogues for centuries.
The Council of Jamnia or Council of Yavne is a hypothetical 1st century council at which it is postulated the canon of the Hebrew Bible was defined.
Some time before the destruction of the Second Temple in 70 AD, Rabbi Yohanan ben Zakkai relocated to the city of Yavne/Jamnia, where he received permission from the Romans to found a school of Halakha (Jewish law). His school became a major source for the later Mishna, which records the Tannaim, and a wellspring of Rabbinic Judaism.
In 1871 Heinrich Graetz, drawing on Mishnaic and Talmudic sources, concluded that there must have been a late 1st century Council of Jamnia which had decided the Jewish canon. This became the prevailing scholarly consensus for much of the 20th century, but from the 1960s onwards it came increasingly into question. In particular, later scholars noted that none of Graetz's sources actually mentioned books that had been withdrawn from a canon, and questioned the whole premise that the discussions of the rabbis were about canonicity at all.