On Baptism, Against the Donatists 10

13. But they think within themselves that they show very great subtlety in asking whether the baptism of Christ in the party of Donatus makes men sons or not; so that, if we allow that it does make them sons, they may assert that theirs is the Church, the mother which could give birth to sons in the baptism of Christ; and since the Church must be one, they may allege that ours is no Church. But if we say that it does not make them sons, "Why then," say they, "do you not cause those who pass from us to you to be born again in baptism, after they have been baptized with us, if they are not thereby born as yet?"

14. Just as though their party gained the power of generation in virtue of what constitutes its division, and not from what causes its union with the Church. For it is severed from the bond of peace and charity, but it is joined in one baptism. And so there is one Church which alone is called Catholic; and whenever it has anything of its own in these communions of different bodies which are separate from itself, it is most certainly in virtue of this which is its own in each of them that it, not they, has the power of generation. For neither is it their separation that generates, but what they have retained of the essence of the Church; and if they were to go on to abandon this, they would lose the power of generation. The generation, then, in each case proceeds from the Church, whose sacraments are retained, from which any such birth can alone in any case proceed,--although not all who receive its birth belong to its unity, which shall save those who persevere even to the end. Nor is it those only that do not belong to it who are openly guilty of the manifest sacrilege of schism, but also those who, being outwardly joined to its unity, are yet separated by a life of sin. For the Church had herself given birth to Simon Magus through the sacrament of baptism; and yet it was declared to him that he had no part in the inheritance of Christ. Did he lack anything in respect of baptism, of the gospel, of the sacraments? But in that he wanted charity, he was born in vain; and perhaps it had been well for him that he had never been born at all. Was anything wanting to their birth to whom the apostle says, "I have fed you with milk, and not with meat, even as babes in Christ"? Yet he recalls them from the sacrilege of schism, into which they were rushing, because they were carnal: "I have fed you," he says, "with milk, and not with meat: for hitherto ye were not able to bear it, neither yet now are ye able. For ye are yet carnal: for whereas there is among you envying and strife, are ye not carnal, and walk as men? For while one saith, I am of Paul; and another, I am of Apollos; are ye not men?" For of these he says above: "Now I beseech you, brethren, by the name of our Lord Jesus Christ, that ye all speak the same thing, and that there be no divisions among you; but that ye be perfectly joined together in the same mind, and in the same judgment. For it hath been declared unto me of you, my brethren, by them which are of the house of Chloe, that there are contentions among you. Now this I say, that every one of you saith, I am of Paul, and I of Apollos, and I of Cephas, and I of Christ. Is Christ divided? was Paul crucified for you? or were ye baptized in the name of Paul?" These, therefore, if they continued in the same perverse obstinacy, were doubtless indeed born, but yet would not belong by the bond of peace and unity to the very Church in respect of which they were born. Therefore she herself bears them in her own womb and in the womb of her handmaids, by virtue of the same sacraments, as though by virtue of the seed of her husband. For it is not without meaning that the apostle says that all these things were done by way of figure. But those who are too proud, and are not joined to their lawful mother, are like Ishmael, of whom it is said, "Cast out this bond-woman and her Son: for the son of the bond-woman shall not be heir with my son, even with Isaac." But those who peacefully love the lawful wife of their father, whose sons they are by lawful descent, are like the sons of Jacob, born indeed of handmaids, but yet receiving the same inheritance. But those who are born within the family, of the womb of the mother herself, and then neglect the grace they have received, are like Isaac's son Esau, who was rejected, God Himself bearing witness to it, and saying, "I loved Jacob, and I hated Esau;" and that though they were twin-brethren, the offspring of the same womb.