The rabbinic sources of the mishnaic era provide very little information on the subject and what information is supplied is almost always subject to dispute as to its exact meaning and historical value. Despite the variety of halachic practices found in the Jewish community in the first century, Christians threatened the Torah principle more seriously than other organized groups in Judaism. The missionary impulse of Christians was bound to antagonize whenever the central symbols of Jewish identity were challenged. Central to a consideration of rabbinic responses to early Christianity is the so-called Birkat ha-Minim. Christianity was of urgent concern to the rabbinic sages between the fall of Jerusalem and the defeat of Bar Kochba. Jewish and other Christians certainly separated themselves for purposes of worship and teaching and social support from the synagogue at an early date, but this was a free choice based on internal Christian needs and wants.