Nicene and Post-Nicene Fathers, Vol. IV:
Writings in Connection with the Donatist Controversy.: Chapter 3

Chapter. 3.—3.  But in what Cyprian adds, saying, "Nor yet because men once have erred must there be always error, since it rather befits wise and God-fearing men gladly and unhesitatingly to follow truth, when it is clearly laid before their eyes, than obstinately and persistently to fight for heretics against their brethren and their fellow-priests," 1473 he is uttering the most perfect truth; and the man who resists the manifest truth is opposing himself rather than his neighbors.  But, so far as I can judge, it is perfectly clear and certain, from the many arguments which I have already adduced, that the baptism of Christ cannot be invalidated even by the perversity of heretics, when it is given or received among them.  But, granting that it is not yet certain, at any rate no one who has considered what has been said, even from a hostile point of view, will assert that the question has been decided the other way.  Therefore we are not striving against manifest truth, but either, as I think, we are striving in behalf of what is clearly true, or, at any rate, as those may hold who think that the question has not yet been solved, we are seeking for the truth.  And therefore, if the truth be other than we think, yet we are receiving those baptized by heretics with the same honesty of heart with which those received them whom, Cyprian supposed, in virtue of their cleaving to the unity of the Church, to be capable of pardon.  But if the baptism of Christ, as is indicated by the many arguments used above, can retain its integrity amid any defect either of life or faith, whether on the part of those who seem to be within, and yet do not belong to the members of the one dove or on the part of those whose severance from her extends to being openly without, then those who sought its repetition in those former days deserved the same pardon for their charity in clinging to unity, which Cyprian thought that those deserved for charity of the same kind whom he believed to have been admitted without baptism.  They therefore who, without any cause (since, as Cyprian himself shows, the bad cannot hurt the good in the unity of the Church), have cut themselves off from the charity which is shown in this unity, have lost all place of pardon, and whilst they would incur destruction by the very crime of schism, even though they did not rebaptize those who had been baptized in the Catholic Church, of how bitter punishment are they deserving, who are either endeavoring to give to the Catholics who have it what Cyprian affirms that they themselves p. 465 have not, or, as is clear from the facts of the case, are bringing as a charge against the Catholic Church that she has not what even they themselves possess?

Footnotes

Cypr. Ep. lxxiii. 23.