A new set of circumstances confronted the tannaitic leadership when it reassembled at Yavneh after the war with Rome was lost. By this time, the need to close ranks and to face the future as a united community was greater than ever. We shall see, though, that the Rabbis still did not elect to see the Jewish Christians as a separate religion. After all, they still met the halakhic criteria for Jewish status. Instead, action would be taken to bar them from officiating as precentors in the synagogue in order to make them feel unwanted there and to exclude their books from sanctified status. Other restrictions would attempt to separate the Jewish Christians from the mainstream Jewish community. Tannaitic law would eventually have to face the Gentile Christians, but the Rabbis as yet had little opportunity for contact with them.
Putting it bluntly, early Christianity was utterly Jewish. The Gentiles involved were following Jewish lead.
HT: Jim West’s Zwinglius Redivivus