“Woe unto you, scribes and Pharisees, hypocrites! for ye compass sea and land to make one proselyte, and when he is made, ye make him twofold more the child of hell than yourselves.”
King James Version (KJV)
Mt 23:15 Ye compass sea and land. Spare no effort. To make one proselyte. Induce Gentiles to become circumcised and to keep the Jewish religion. This is the sense in which "proselyte" was then always used. Twofold more the child of hell. Usually the proselytes of such teachers went to even more sectarian extremes than their teachers.