Which phenomenon most directly led to Christianity separating from Judaism

By the First Century A. D., both Judaism and Christianity shared a common belief in the Messiah though in different ways: while Judaism was still expecting the advent of the Messiah, particularly a warrior-like Messiah who would deliver the Jews from Roman oppression by the force of arms, Christians were already certain that the Messiah had come along in the person of Jesus of Nazareth, a. k. a. Jesus Christ. Also, the openness of Christianity to "Gentiles" (non Jews) and people from all walks of life set it apart from Judaism forever, since Judaism only embraced people born from Jewish parents and rejected all Gentiles. A discussion between apostles Paul and Peter over the mandatory aspect of circumcision (a must in Judaism) for new Gentile members, made it clear that Christianity had sprung off from Judaism as an independent creed when it was settled that traditional Judaic practices such as circumcision, the ban on impure foods (kosher), etc. were not necessary to become a good Christian.