They went out from us, but they were not of us; for if they had been of us, they would no doubt have continued with us: but they went out, that they might be made manifest that they were not all of us.
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Augustine of Hippo
AD 430
If then they went out from us, they are antichrists; if they are antichrists, they are liars; if they are liars, they deny that Jesus is the Christ. Once more we come back to the difficulty of the question. Ask them one by one; they confess that Jesus is the Christ. The difficulty that hampers us comes of our taking what is said in the Epistle in too narrow a sense. At any rate you see the question; this question puts both us and them to a stand, if it be not understood. Either we are antichrists, or they are antichrists; they call us antichrists, and say that we went out from them; we say the like of them. But now this epistle has marked out the antichrists by this cognizance: Whosoever denies that Jesus is the Christ, that same is an antichrist. Now therefore let us enquire who denies; and let us mark not the tongue, but the deeds. For if all be asked, all with one mouth confess that Jesus is the Christ. Let the tongue keep still for a little while, ask the life. If we shall find thi...
Has once learned, never departs from Him at all, and that those are the Church who remain in the house of God; but that, on the other hand, they are not the plantation planted by God the Father, whom we see not to be established with the stability of wheat, but blown about like chaff by the breath of the enemy scattering them, of whom John also in his epistle says, "They went out from us, but they were not of us; for if they had been of us, no doubt they would have continued with us.".
The Apostle John execrates and severely assails these, when he says, "They went forth from us, but they were not of us; for if they had been of us, surely they would have continued with us."
They were not of us, true and profitable members; though it can scarce be doubted but that some of them, at least for some time, truly believed: and by their going off, God was pleased to make it manifest that they were not of his faithful members. Such were Simon Magus, Cerinthus, Ebion, Nicolas of Antioch (Witham)
They That is, they were not solid, steadfast, genuine Christians, otherwise they would have remained in the Church. (Challoner)
The true note or mark of heresy, is the going out of or leaving the Catholic Church. God permitteth some to go out, that the true and tried faithful may be known.
