Nicene and Post-Nicene Fathers, Vol. IV:
Writings in Connection with the Donatist Controversy.: Chapter 19

Chapter 19.—25.  Wherefore, as regards those who received the persons who came from heresy in the same baptism of Christ with which they had been baptized outside the Church, and said "that they followed ancient custom," as indeed the Church now receives such, it is in vain urged against them "that among the ancients there were as yet only the first beginning of heresy and schisms, 1518 so that those were involved in them who were seceders from the Church, and had originally been baptized within the Church, so that it was not necessary that they should be baptized again when they returned and did penance."  For so soon as each several heresy existed, and departed from the communion of the Catholic Church, it was possible that, I will not even say the next day, but even on that very day, its votaries might have baptized some who flocked to them.  And therefore if this was the old custom, that they should be so received into the Church (as could not be denied even by those who maintained the contrary part in the discussion), there can be no doubt in the mind of any one who pays careful attention to the matter, that those also were so received who had been baptized without in heresy.

26.  But I cannot see what show of reason there is in this, that the name of "erring sheep" 1519 should be denied to one whose lot it has been that, while seeking the salvation which is in Christ, he has fallen into the error of heretics, and been baptized in their body; while he is held to have become a sheep alp. 473 ready within the body of the Catholic Church herself, who has renounced the world in words and not in deeds, and has received baptism in such falseness of heart as this.  Or if such an one also does not become a sheep unless after turning to God with a true heart, then, as he is not baptized at the time when he becomes a sheep, if he had been already baptized, but was not yet a sheep; so he too, who comes from the heretics that he may become a sheep, is not then to be baptized if he had been already baptized with the same baptism, though he was not yet a sheep.  Wherefore, since even all the bad that are within—the covetous, the envious, the drunkards, and those that live contrary to the discipline of Christ—may be deservedly called liars, and in darkness, and dead, and antichrists, do they yet therefore not baptize, on the ground that "there can be nothing common between truth and falsehood, between light and darkness, between death and immortality, between Antichrist and Christ?" 1520

27.  He makes an assumption, then, not "of mere custom," but "of the reason of truth itself," 1521 when he says that the sacrament of God cannot be turned to error by the error of any men, since it is declared to exist even in those who have erred.  Assuredly the Apostle John says most plainly, "He that hateth his brother is in darkness even until now;" 1522 and again, "Whosoever hateth his brother is a murderer;" 1523 and why, therefore, do they baptize those within the Church whom Cyprian himself declares to be in the envy of malice? 1524

Footnotes

Apud veteres hæreses et schismata prima adhuc fuisse initia; that among the ancients heresies and schisms were yet in their very infancy.  Benedictines suggest:  "hæresis et schismatum."  Hartel reads:  apud veteres hæreseos et schismatum prima adhuc fuerint initia.

Cypr. Ep. lxxi. 2.

Cypr. Ep. lxxi. 2.

Cypr. Ep. lxxi. 3.

1 John ii. 9.

1 John iii. 15.

Cypr. Ep. lxxiii. 14.