27 And, in the first place, with regard to that first expression, "Of him who gives in holiness," it does not interfere in the least with my inquiry, by which he is so much distressed, whether I use the expression, "If the conscience of him that gives is what we look for," or the fuller phrase, "If the conscience of him that gives in holiness is what we look for, to cleanse the conscience of the recipient," by what means then is he to be cleansed who receives baptism if the conscience of the giver is polluted, without the knowledge of him who is to receive the sacrament?
And with regard to the other word that is added, "wittingly," so that the sentence should not run, "He who has received his faith from one that is faithless," but "He who has wittingly received his faith from one that is faithless, receives not faith but guilt," I confess that I had said some things as though the word were absent, but I can easily afford to do without them; for they caused more hindrance to the facility of my argument than they gave assistance to its power. For how much more readily, how much more plainly and shortly, can I put the question thus: "If the conscience of him who gives in holiness is what we look for to cleanse the conscience of the recipient," and "if he who has wittingly received his faith from one that is faithless receives not faith but guilt," by what means is he cleansed, from whom the stain on the conscience of him who gives, but not in holiness, is hidden?
And whence does he receive true faith, who is baptized unwittingly by one that is faithless? Let it be declared whence this shall be, and then the whole theory of baptism will be disclosed; then all that is matter of investigation will be brought to light—but only if it be declared, not if the time be consumed in evil-speaking.
Source: Answer to Letters of Petilian, Bishop of Cirta (New Advent)