This quote below clears up many of the differences between three separate religious groups from A.D. 31 to A.D. 325. These are the Jews, the Natsarim, and the Christians.
“But these sectarians… did not call themselves Christians – but “Nazarenes” [Natsarim] . . . However they are simply complete Jews. They use not only the New Testament but the Old Testament as well, as the Jews do… They have no different ideas, but confess everything exactly as the Law proclaims it and in the Jewish fashion – except for their belief in Messiah, if you please! For they acknowledge both the resurrection of the dead and the divine creation of all things, and declare that God is one, and that His son is Yahusha the Messiah. They are trained to a nicety in Hebrew. For among them the entire Law (Torah), the Prophets, and the… Writings … are read in Hebrew, as they surely are by the Jews. They are different from the Jews, and different from Christians, only in the following. They disagree with Jews because they have come to faith in Messiah; but since they are still fettered by the Law – circumcision, the Sabbath, and the rest – they are not in accord with Christians . . . they are nothing but Jews… They have the Gospel according to Matthew in its entirety in Hebrew. For it is clear that they still preserve this, in the Hebrew alphabet, as it was originally written.” Epiphanius; Panarion 29:9:4, A.D. 374.