4 And if they would have obeyed him, and begun to live rightly, not as false but as true Christians, would he have ordered them to be baptized anew? Surely not; but their true conversion would have gained this for them, that the sacrament which availed for their destruction while they were yet unchanged, should begin when they changed to avail for their salvation.
5. For neither are they "devoted to the Church" who seem to be within and live contrary to Christ, that is, act against His commandments; nor can they be considered in any way to belong to that Church, which He so purifies by the washing of water, "that He may present to Himself a glorious Church, not having spot or wrinkle, or any such thing." But if they are not in that Church to whose members they do not belong, they are not in the Church of which it is said, "My dove is but one; she is the only one of her mother;" for she herself is without spot or wrinkle. Or else let him who can assert that those are members of this dove who renounce the world in words but not in deeds. Meantime there is one thing which we see, from which I think it was said, "He that regards the day, regards it unto the Lord," for God judges every day. For, according to His foreknowledge, who knows whom He has foreordained before the foundation of the world to be made like to the image of His Son, many who are even openly outside, and are called heretics, are better than many good Catholics. For we see what they are today, what they shall be tomorrow we know not. And with God, with whom the future is already present, they already are what they shall hereafter be. But we, according to what each man is at present, inquire whether they are to be today reckoned among the members of the Church which is called the one dove, and the Bride of Christ without a spot or wrinkle, of whom Cyprian says in the letter which I have quoted above, that "they did not keep in the way of the Lord, nor observe the commandments given unto them for their salvation; that they did not fulfill the will of their Lord, being eager about their property and gains, following the dictates of pride, giving way to envy and dissension, careless about single-mindedness and faith, renouncing the world in words only and not in deeds, pleasing each himself, and displeasing all men." But if the dove does not acknowledge them among her members, and if the Lord shall say to them, supposing that they continue in the same perversity, "I never knew you: depart from me, you that work iniquity;" then they seem indeed to be in the Church, but are not; "nay, they even act against the Church. How then can they baptize with the baptism of the Church," which is of avail neither to themselves, nor to those who receive it from them, unless they are changed in heart with a true conversion, so that the sacrament itself, which did not avail them when they received it while they were renouncing the world in words and not in deeds, may begin to profit them when they shall begin to renounce it in deeds also? And so too in the case of those whose separation from the Church is open; for neither these nor those are as yet among the members of the dove, but some of them perhaps will be at some future time.
Source: On Baptism, Against the Donatists (New Advent)