1 John 4:2

Verse 2. By this is the Spirit of God known. He gives the new converts first this general mark, by which they might have good grounds to think that the teachers they met with in those days had a good spirit, were of God, if they confessed and acknowledged Jesus Christ to have come from heaven and to have been made flesh, or made man; that is to be truly God and truly man. But if (verse 3) they met with teachers of such a spirit as dissolveth Jesus, [1] by denying him either to be the Messias or to be truly God, or to be a true man, they might conclude for certain that such men had not a true spirit, but were heretics, antichrists, and forerunners of the great antichrist. Such, even in Saint John’s time, was Simon the magician, who, according to S. Epiphan. (hær. xxi. p. 55. Ed Petav.) pretended among his countrymen, the Samaritans, that he himself was God the Father, and among the Jews that he was God the Son, and that Jesus suffered death in appearance only. His disciple also, Menander, said he was sent from heaven for the salvation of men. See S. Epiphan. hær. xxii. p. 61. 3. Cerinthus, as also Carpocras, held that Jesus was a mere man, born of Joseph and Mary, and also different from Christ. See S. Epiphan. hær. xxxvii. and xxix. p. 102. and 110. 4. Ebion held much the same. See the same S. Epiphan. hær. xxx. p. 142. These heretics and divers of their followers divided Jesus, and destroyed the faith and mystery of the incarnation. Witham.—Every spirit which confesseth, and so forth Not that the confession of this point of faith alone, is at all times and in all cases sufficient; but that with relation to that time, and for that part of the Christian doctrine, which was then particularly to be confessed, taught, and maintained against the heretics of those days, this was the most proper token by which the true teachers might be distinguished from the false. Challoner.