Just, then, as “Paul [was] an apostle, not of men, neither by man, but by Jesus Christ, and God the Father" the Son indeed leading them to the Father, but the Father revealing to them the Son. [Irenaeus 3.13.2]
and Tertullian:
He himself, says Marcion, claims to be an apostle, and that not from men nor through any man, but through Jesus Christ. [Tertullian Against Marcion 5.1]
There is also Irenaeus's unique citations of 1 John 4:2,3:
These are they against whom the Lord has cautioned us beforehand; and His disciple, in his Epistle already mentioned, commands us to avoid them, when he says: “For many deceivers are entered into the world, who confess not that Jesus Christ is come in the flesh. This is a deceiver and an antichrist. Take heed to them, that ye lose not what ye have wrought.” And again does he say in the Epistle: “Many false prophets are gone out into the world. Hereby know ye the Spirit of God: Every spirit that confesseth that Jesus Christ is come in the flesh is of God; and every spirit which separates Jesus Christ is not of God, but is of antichrist.” These words agree with what was said in the Gospel, that “the Word was made flesh, and dwelt among us.” [Irenaeus Against Heresies 3.14.8]
which is shared by Tertullian:
According indeed to our view, he is Antichrist; as it is taught us in both the ancient and the new prophecies, and especially by the Apostle John, who says that “already many false prophets are gone out into the world,” the fore-runners of Antichrist, who deny that Christ is come in the flesh and separate Jesus (solventes Jesum) [Tertullian Against Marcion 5.16]
Interesting also that both Irenaeus and Tertullian in Against Marcion connect 1 Cor 1.23 and Isa 8:14 (AH 3.18.2 and AM 5.5)
