18 Nemesianus of Tubunæ said: "That the baptism which is given by heretics and schismatics is not true is everywhere declared in the holy Scriptures, inasmuch as their very prelates are false Christs and false prophets, as the Lord declares by the mouth of Solomon, 'Whoso trusts in lies, the same feeds the winds; he also follows flying birds. For he deserts the ways of his own vineyard, and has strayed from the paths of his own field. For he walks through pathless and dry places, and a land destined to thirst; and he gathers fruitless weeds in his hands.' And again, 'Abstain from strange water, and drink not of a strange fountain, that you may live long, and that years may be added to your life.' And in the gospel our Lord Jesus Christ spoke with His own voice, saying, 'Unless a man be born of water and of the Spirit, he cannot enter into the kingdom of God.' This is the Spirit which from the beginning 'moved upon the face of the waters.' For neither can the Spirit act without the water, nor the water without the Spirit. Ill, therefore, for themselves do some interpret, saying that by imposition of hands they receive the Holy Ghost, and are received into the Church, when it is manifest that they ought to be born again by both sacraments in the Catholic Church. For then indeed will they be able to become the sons of God, as the apostle says, 'Endeavoring to keep the unity of the Spirit in the bond of peace. There is one body, and one Spirit, even as you are called in one hope of your calling; one Lord, one faith, one baptism, one God.' All this the Catholic Church asserts. And again he says in the gospel, 'That which is born of the flesh is flesh, and that which is born of the Spirit is spirit; for the Spirit is God, and is born of God.' Therefore all things whatsoever all heretics and schismatics do are carnal, as the apostle says, 'Now the works of the flesh are manifest, which are these: fornication, uncleanness, lasciviousness, idolatry, witchcraft, hatred, variance, emulations, wrath, seditions, heresies, and such like: of the which I tell you before, as I have also told you in time past, that they which do such things shall not inherit the kingdom of God.' The apostle condemns, equally with all the wicked, those also who cause divisions, that is, schismatics and heretics. Unless therefore they receive that saving baptism which is one, and found only in the Catholic Church, they cannot be saved, but will be condemned with the carnal in the judgment of the Lord."
19. Nemesianus of Tubunæ has advanced many passages of Scripture to prove his point; but he has in fact said much on behalf of the view of the Catholic Church, which we have undertaken to set forth and maintain. Unless, indeed, we must suppose that he does not "trust in what is false" who trusts in the hope of things temporal, as do all covetous men and robbers, and those "who renounce the world in words but not in deeds," of whom Cyprian yet bears witness that such men not only baptize, but even are baptized within the Church. For they themselves also "follow flying birds," since they do not attain to what they desire. But not only the heretic, but everyone who leads an evil life "deserts the ways of his own vineyard, and has strayed from the paths of his own field. And he walks through pathless and dry places, and a land destined to thirst; and he gathers fruitless weeds in his hands;" because all justice is fruitful, and all iniquity is barren. Those, again, who "drink strange water out of a strange fountain," are found not only among heretics, but among all who do not live according to the teaching of God, and do live according to the teaching of the devil. For if he were speaking of baptism, he would not say, "Do not drink of a strange fountain," but, do not wash yourself in a strange fountain. Again, I do not see at all what aid he gets towards proving his point from the words of our Lord, "Unless a man be born of water and of the Spirit, he cannot enter into the kingdom of God." For it is one thing to say that every one who shall enter into the kingdom of heaven is first born again of water and the Spirit, because except a man be born of water and of the Spirit, he shall not enter into the kingdom of heaven, which is the Lord's saying, and is true; another thing to say that every one who is born of water and the Spirit shall enter into the kingdom of heaven, which is assuredly false. For Simon Magus also was born of water and of the Spirit, and yet he did not enter into the kingdom of heaven; and this may possibly be the case with heretics as well. Or if only those are born of the Spirit who are changed with a true conversion, all "who renounce the world in word and not in deed" are assuredly not born of the Spirit, but of water only, and yet they are within the Church, according to the testimony of Cyprian. For we must perforce grant one of two things—either those who renounce the world deceitfully are born of the Spirit, though it is to their destruction, not to salvation, and therefore heretics may be so born; or if what is written, that "the Holy Spirit of discipline will flee deceit," extends to proving as much as this, that those who renounce the world deceitfully are not born of the Spirit, then a man may be baptized with water, and not born of the Spirit, and Nemesianus says in vain that neither the Spirit can work without the water, nor the water without the Spirit. Indeed it has been already often shown how it is possible that men should have one baptism in common who have not one Church, as it is possible that in the body of the Church herself those who are sanctified by their righteousness, and those who are polluted through their covetousness, may not have the same one Spirit, and yet have the same one baptism. For it is said "one body," that is, the Church, just as it is said "one Spirit" and "one baptism." The other arguments which he has adduced rather favor our position. For he has brought forward a proof from the gospel, in the words, "That which is born of the flesh is flesh, and that which is born of the Spirit is spirit; for the Spirit is God, and born of God;" and he has advanced the argument that therefore all things that are done by any heretic or schismatic are carnal, as the apostle says, "The works of the flesh are manifest, which are these: fornication, uncleanness;" and so he goes through the list which the apostle there enumerates, among which he has reckoned heresies, since "they who do such things shall not inherit the kingdom of God." Then he goes on to add, that "therefore the apostle condemns with all wicked men those also who cause division, that is, schismatics and heretics." And in this he does well, that when he enumerates the works of the flesh, among which are also heresies, he found and declared that the apostle condemns them all alike. Let him therefore question the holy Cyprian himself, and learn from him how many even within the Church live according to the evil works of the flesh, which the apostle condemns in common with the heresies, and yet these both baptize and are baptized. Why then are heretics alone said to be incapable of possessing baptism, which is possessed by the very partners in their condemnation?
Source: On Baptism, Against the Donatists (New Advent)