13 What, then, do you wish to take away? What displeases you in the man whom you wish to rebaptize? You are not able to give what he already has, but you make him deny what he has. What greater cruelty did the pagan persecutor of the Church commit? Swords were stretched out against the martyrs, wild beasts were let loose, fires were applied: for what purpose these things? In order that the sufferer might be induced to say, I am not a Christian. What do you teach him whom you wish to rebaptize, unless that he first say, I am not a Christian?
For the same purpose for which the persecutor put forth the flame, you put forth the tongue; you do by seducing what he did not do by slaying. And what is it you give, and to whom are you to give it? If he tells you the truth, and does not lie, seduced by you, he will say, I have. Thou ask, Have you baptism? I have, he says. As long as he says, I have, you say, I will not give. And do not give, for that which you wish to give cannot cleave to me; because what I received cannot be taken away from me.
But wait, nevertheless; let me see what you would teach me. Say, he said, in the first place, I have not. But this I have; if I shall say, I have not, I lie; for what I have I have. You have not, he says. Teach me that I have it not. An evil man gave it to you. If Christ is evil, an evil man did give it to me. Christ, he says, is not evil; but Christ did not give it to you. Who then gave it to me? Reply, I know that I received it from Christ. He who gave it to you, he says, was not Christ, but some traditor.
I shall see to it who was the minister; I shall see who was the herald. Concerning the official, I do not dispute; I give heed to the Judge: and, perchance, in your objection to the official, you speak falsely. But I decline to discuss it; let the Lord of both decide the cause of His own official. If, perhaps, I were to ask for proof, you could give none; indeed, you lie, it has been proved that you were not able to give proof. But I do not place my case on this, lest from my zealous defense of innocent men you infer that I have placed my hope even on innocent men.
Let the men be what they may, I received from Christ, I was baptized by Christ. No, he says; not Christ, but that bishop baptized you, and that bishop communicates to them. By Christ I have been baptized, I know. How do you know? The dove taught me, which John saw. O evil kite, you may not tear me from the bowels of the dove. I am numbered among the members of the dove, because what the dove taught, this I know. You say to me, This man or that baptized you: by means of the dove it is said to me and to you, “This is He which baptizes.” Which shall I believe, the kite or the dove?
Source: Tractates on the Gospel of John (New Advent)