Nicene and Post-Nicene Fathers, Vol. IV:
Writings in Connection with the Donatist Controversy.: Chapter 34

Chapter 34.—39.  Petilianus quotes also the warning of the Apostle John, that we should not believe every spirit, but try the spirits whether they are of God, 2396 as though this care should be bestowed in order that the wheat should be separated from the chaff in p. 613 this present world before its time, and not rather for fear that the wheat should be deceived by the chaff; or as though, even if the lying spirit should have said something that was true, it was to be denied, because the spirit whom we should abominate had said it.  But if any one thinks this, he is mad enough to contend that Peter ought not to have said, "Thou art the Christ, the Son of the living God," 2397 because the devils had already said something to the same effect. 2398   Seeing, therefore, that the baptism of Christ, whether administered by an unrighteous or a righteous man, is nothing but the baptism of Christ what a cautious man and faithful Christian should do is to avoid the unrighteousness of man, not to condemn the sacraments of God.

40.  Assuredly in all these things Petilianus gives no answer to the question, If the conscience of one that gives in holiness is what we look for to cleanse the conscience of the recipient, by what means is he to be cleansed who receives baptism, when the conscience of the giver is polluted without the knowledge of the proposed recipient?  A certain Cyprian, a colleague of his from Thubursicubur, was caught in a brothel with a woman of most abandoned character, and was brought before Primianus of Carthage, and condemned.  Now, when this man baptized before he was detected and condemned, it is manifest that he had not the conscience of one that gives in holiness, so as to cleanse the conscience of the recipient.  By what means then have they been cleansed who at this day, after he has been condemned, are certainly not washed again?  It was not necessary to name the man save only to prevent Petilianus from repeating, "Who is the man, and from what corner has he started up, that you propose to us?"  Why did not your party examine that baptizer, as John, in the opinion of Petilianus, was examined?  Or was the real fact this, that they examined him so far as man can examine man, but were unable to find him out, as he long lay hid with cunning falseness?

Footnotes

1 John iv. 1.

Matt. xvi. 16.

Matt. 8:29, Mark 1:24, Luke 8:28.