John Chrysostom, on Rom 3:8

"If not (as some affirm that we say,) Let us do evil that good may come? Whose damnation is just." For whereas Paul said, "where sin abounded grace did much more abound" (Rom. v. 20), in ridicule of him and perverting what he said to another meaning, they said, We must cling to vice that we may get what is good. But Paul said not so; however to correct this notion it is that he says, "What then? shall we continue in sin that grace may abound? God forbid!" (ib. vi. 1, 2.) For I said it, he means, of the times which are past, not that we should make this a practice. To lead them away then from this suspicion, he said, that henceforth this was even impossible. For "how shall we," he says, "that are dead unto sin, live any longer therein?" Against the Greeks then he inveighs without difficulty. For their life was exceeding abandoned. But of the Jews, even if their life seemed to have been careless, still they had great means of cloaking these things in the Law and circumcision, and the fact of God having conversed with them, and their being the teachers of all. And this is why he strips them even of these, and shows that for these they were the more punished, and this is the conclusion to which he has here drawn his discussion.