From “Tractate 62,” Tractates in Saint John’s Gospel (419)

It was after this bread, then, that Satan entered into the Lord’s betrayer, that, as now given over to his power, he might take full possession of one into whom before this he had only entered in order to lead him into error. For we are not to suppose that Satan was not in him when he went to the Jews and bargained about the price of betraying the Lord; for the evangelist Luke very plainly attests this when he says: “Then entered Satan into Judas, who was surnamed Iscariot, being one of the twelve; and he went his way, and communed with the chief priests” (Luke 22:3-4).

Here, you see, it is shown that Satan had already entered into Judas. His first entrance, therefore, was when he implanted in his heart the thought of betraying Christ; for in such a spirit had he already come to the supper. But now, after the bread, he entered into him, no longer to tempt one who belonged to another, but to take possession of him as his own…

But still, possessed as Judas now was, not by the Lord, but by the devil, and now that the bread had entered the belly, and an enemy the soul of this man of ingratitude; still, I say, there was this enormous wickedness, already conceived in his heart, waiting to be wrought out to its full issue, for which the damnable desire had always preceded.

Accordingly, when the Lord, the living Bread, had given this bread to the dead, and in giving it had revealed the betrayer of the Bread, he said, “What you do, do quickly.” He did not command the crime, but foretold evil to Judas, and good to us. For what could be worse for Judas, or what could be better for us, than the delivering up of Christ — a deed done by him to his own destruction, but done, apart from him, in our behalf?

“What you do, do quickly.” Oh that word of one whose wish was to be ready rather than to be angry! That word! expressing not so much the punishment of the traitor as the reward awaiting the Redeemer! For he said, “What you do, do quickly,” not as wrathfully looking to the destruction of the trust-betrayer, but in his own haste to accomplish the salvation of the faithful; for “he was delivered for our offenses,” (Rom. 4:25) and he loved the Church, and gave himself for it. (Eph. 5:25). And as the apostle also says of himself: “Who loved me, and gave himself for me” (Gal. 2:20). Had not, then, Christ given himself, no one could have given him up.

What is there in Judas’ conduct but sin? For in delivering up Christ he had no thought of our salvation, for which Christ was really delivered, but thought only of his monetary gain, and found the loss of his soul. He got the wages he wished, but had also given him, against his wish, the wages he merited. Judas delivered up Christ, Christ delivered himself up: the former transacted the business of his own selling of his Master, the latter the business of our redemption. “What you do, do quickly,” not because you have the power in yourself, but because he wills it who has all the power.

St. Augustine (354-430) was a theologian and philosopher who served as Bishop of Hippo Regius in North Africa. He was a voluminous author, whose writings about God’s grace, the Sacraments, and the Church have been profoundly influential in the development of Western Christianity. His Tractates on John, a series of brief expository sermons, were written to guide other clergy in the art of preaching. His feast day is August 26.