Nicene and Post-Nicene Fathers, Vol. IV:
Writings in Connection with the Donatist Controversy.: Chapter 15

Chapter 15.—23.  To go on to the point which he pursues at great length, that "they who blaspheme the Father of Christ cannot be baptized in Christ," 1435 since it is clear that they blaspheme through error (for he who comes to the baptism of Christ will not openly blaspheme the Father of Christ, but he is led to blaspheme by holding a view contrary to the teaching of the truth about the Father of Christ), we have already shown at sufficient length that baptism, consecrated in the words of the gospel, is not affected by the error of p. 457 any man, whether ministrant or recipient, whether he hold views contrary to the revelation of divine teaching on the subject of the Father, or the Son, or the Holy Ghost.  For many carnal and natural men are baptized even within the Church, as the apostle expressly says:  "The natural man receiveth not the things of the Spirit of God;" 1436 and after they had received baptism, he says that they "are yet carnal." 1437   But according to it carnal sense, a soul given up to fleshly appetites cannot entertain but fleshly wisdom about God.  Wherefore many, progressing after baptism, and especially those who have been baptized in infancy or early youth, in proportion as their intellect becomes clearer and brighter, while "the inward man is renewed day by day," 1438 throw away their former opinions which they held about God while they were mocked with vain imaginings, with scorn and horror and confession of their mistake.  And yet they are not therefore considered not to have received baptism, or to have received baptism of a kind corresponding to their error; but in them both the perfection of the sacrament is honored and the delusion of their mind is corrected, even though it had become inveterate through long confirmation, or been, perhaps, maintained in many controversies.  Wherefore even the heretic, who is manifestly without, if he has there received baptism as ordained in the gospel, has certainly not received baptism of a kind corresponding to the error which blinds him.  And therefore, in returning into the way of wisdom he perceives that he ought to relinquish what he has held amiss, he must not at the same time give up the good which he had received; nor because his error is to be condemned, is the baptism of Christ in him to be therefore extinguished.  For it is already sufficiently clear, from the case of those who happen to be baptized within the Church with false views about God, that the truth of the sacrament is to be distinguished from the error of him who believes amiss, although both may be found in the same man.  And therefore, when any one grounded in any error, even outside the Church, has yet been baptized with the true sacrament, when he is restored to the unity of the Church, a true baptism cannot take the place of a true baptism, as a true faith takes the place of a false one, because a thing cannot take the place of itself, since neither can it give place.  Heretics therefore join the Catholic Church to this end, that what they have evil of themselves may be corrected, not that what they have good of God should be repeated.

Footnotes

Ib. Ep. lxxiii. 17.

1 Cor. ii. 14.

1 Cor. iii. 3.

2 Cor. iv. 16.