On Baptism by Tertullian
Chapter XV.--Unity of Baptism. Remarks on Heretical And Jewish Baptism.
I know not whether any further point is mooted to bring baptism into controversy. Permit me to call to mind what I have omitted above, lest I seem to break off the train of impending thoughts in the middle. There is to us one, and but one, baptism; as well according to the Lord's gospel as according to the apostle's letters, inasmuch as he says, |One God, and one baptism, and one church in the heavens.| But it must be admitted that the question, |What rules are to be observed with regard to heretics?| is worthy of being treated. For it is to us that that assertion refers. Heretics, however, have no fellowship in our discipline, whom the mere fact of their excommunication testifies to be outsiders. I am not bound to recognize in them a thing which is enjoined on me, because they and we have not the same God, nor one -- that is, the same -- Christ. And therefore their baptism is not one with ours either, because it is not the same; a baptism which, since they have it not duly, doubtless they have not at all; nor is that capable of being counted which is not had. Thus they cannot receive it either, because they have it not. But this point has already received a fuller discussion from us in Greek. We enter, then, the font once: once are sins washed away, because they ought never to be repeated. But the Jewish Israel bathes daily, because he is daily being defiled: and, for fear that defilement should be practised among us also, therefore was the definition touching the one bathing made. Happy water, which once washes away; which does not mock sinners (with vain hopes); which does not, by being infected with the repetition of impurities, again defile them whom it has washed!