Tertullian

“ On this point, however, we dwell no longer, since it is the same Paul who, in his Epistle to the Galatians, counts “heresies” among “the sins of the flesh,” [1] who also intimates to Titus, that “a man who is a heretic” must be “rejected after the first admonition,” on the ground that “he that is such is perverted, and committeth sin, as a self-condemned man.” ”

“ Of these the practical effects [4] are false doctrines, called in Greek heresies, [5] a word used in the sense of that choice which a man makes when he either teaches them (to others) [6] or takes up with them (for himself) . [7] For this reason it is that he calls the heretic self-condemned, [8] because he has himself chosen that for which he is condemned. We, however, are not permitted to cherish any object [9] after our own will, nor yet to make choice of that which another has introduced of his private fancy. In the Lord’s apostles we possess our authority ”