Tertullian

“ I require to know of Marcion the origin of his apostle [3] even—I, who am to some degree a new disciple, [4] the follower of no other master; who at the same time [5] can believe nothing, except that nothing ought to be believed hastily [6] (and that I may further say is hastily believed, which is believed without any examination [7] of its beginning) ; in short, I who have the best reason possible for bringing this inquiry to a most careful solution, [8] since a man is affirmed to me to be an apostle whom I do not find mentioned in the Gospel in the catalogue [9] of the apostles. ”

“ It is not at all likely that he would call men away from Judaism without showing them at the same time what was the god in whom he invited them to believe; because nobody could possibly pass from allegiance to the Creator without knowing to whom he had to cross over. ”

“ He professes himself to be “an apostle”—to use his own, words—“not of men, nor by man, but by Jesus Christ.” [20] Of course, any one may make a profession concerning himself; but his profession is only rendered valid by the authority of a second person. One man signs, another countersigns; [21] one man appends his seal, another registers in the public records. [22] No one is at once a proposer and a seconder to himself. ”