Isaias 43:18

Every opinion and the whole scheme of the impious and sacrilegious Marcion we now bring to the test of that very Gospel which, by his process of interpolation, he has made his own. To encourage a belief of this Gospel he has actually devised for it a sort of dower, in a work composed of contrary statements set in opposition, thence entitled Antitheses , and compiled with a view to such a severance of the law from the gospel as should divide the Deity into two, nay, diverse, gods, one for each Instrument, or Testament as it is more usual to call it; that by such means he might also patronize belief in “the Gospel according to the Antitheses.” These, however, I would have attacked in special combat, hand to hand; that is to say, I would have encountered singly the several devices of the Pontic heretic, if it were not much more convenient to refute them in and with that very gospel to which …

I am accustomed in my prescription against all heresies, to fix my compendious criterion (of truth) in the testimony of time ; claiming priority therein as our rule, and alleging lateness to be the characteristic of every heresy. This shall now be proved even by the apostle, when he says: “For the hope which is laid up for you in heaven, whereof ye heard before in the word of the truth of the gospel; which is come unto you, as it is unto all the world.” For if, even at that time, the tradition of the gospel had spread everywhere, how much more now! Now, if it is our gospel which has spread everywhere, rather than any heretical gospel, much less Marcion’s, which only dates from the reign of Antoninus, then ours will be the gospel of the apostles. But should Marcion’s gospel succeed in filling the whole world, it would not even in that case be entitled to the character of apostolic. …

8. But as often as water is named alone in the Holy Scriptures, baptism is referred to, as we see intimated in Isaiah: “Remember not,” says he, “the former things, and consider not the things of old. Behold, I will do a new thing, which shall now spring forth; and ye shall know it. I will even make a way in the wilderness, and rivers in the dry place, to give drink to my elected people, my people whom I have purchased, that they might show forth my praise.” There God foretold by the prophet, that among the nations, in places which previously had been dry, rivers should afterwards flow plenteously, and should provide water for the elected people of God, that is, for those who were made sons of God by the generation of baptism. …

In Isaiah: “Therefore remember ye not the former things, neither reconsider the ancient things. Behold, I make new the things which shall now arise, and ye shall know it; and I will make in the desert a way, and rivers in a dry place, to give drink to my chosen race, my people whom I acquired, that they should show forth my praises.” In the same also: “If they thirst, He will lead them through the deserts; He will bring forth water from the rock; the rock shall be cloven, and the water shall flow: and my people shall drink.” Moreover, in the Gospel according to Matthew, John says: “I indeed baptize you with water unto repentance: but He that cometh after me is mightier than I, whose shoes I am not worthy to bear; He shall baptize you with the Holy Ghost, and with fire.” Also according to John: “Except a man be born of water, and of the Spirit, he cannot enter into the kingdom of God. …