AD 70s–80s · Yavneh — shortly after the destruction of the Temple
The Curse in the Synagogue Prayer, the Birkat ha-Minim — Separation from the Synagogue Begins
What it is — a prayer of malediction placed as the twelfth benediction of the daily synagogue prayer, the Eighteen Benedictions (the Amidah, Shemoneh Esreh). Birkat ha-Minim means “the benediction concerning the heretics (minim)”; in substance it is a curse upon them. The Talmud records that Samuel the Small composed it at the request of Rabban Gamaliel II.
When — after the destruction of the Temple in AD 70, in the 70s and 80s, when the rabbis gathered at Yavneh and reordered synagogue worship, it began to be placed in the synagogue prayer.
What followed — Jewish believers in Yeshua could not join in this prayer in synagogue worship, and one who omitted this benediction when leading the prayer fell under suspicion. From this prayer, which kept believers in Yeshua from coming to the synagogue, the believers began to be separated gradually from the synagogue. In the mid-second century Justin records that the Jews “curse in your synagogues those who believe in Christ,” and in the fourth century Jerome and Epiphanius report that the synagogues cursed the “Nazarenes” (notzrim). (The original wording of the malediction and its scope remain under scholarly discussion.)
Babylonian Talmud, Berakhot 28b–29a · Justin, Dialogue with Trypho 16, 96 · Jerome, Commentary on Isaiah 5.18–19 · Epiphanius, Panarion 29.9