He solves one perplexity by another again. Yet as this is not clear, we must needs declare it more clearly. What is it then he means? God honored the Jews: they did despite to Him. This gives Him the victory, and shows the greatness of His love towards man, in that He honored them even such as they were. Since then, he means, we did despite to Him and wronged Him, God by this very thing became victorious, and His righteousness was shown to be clear. Why then (a man may say) am I to be punished, who have been the cause of His victory by the despite I did Him? Now how does he meet this? It is, as I was saying, by another absurdity again. For if it were you, he says, that were the cause of the victory, and after this are punished, the thing is an act of injustice. But if He is not unjust, and yet you are punished, then you are no more the cause of the victory. And note his apostolic reverence; (or caution: εὐλάβεια]); for after saying, "Is God unrighteous Who takes vengeance?" he adds, "I speak as a man." As if, he means, any body were to argue in the way men reason. For what things seem with us to be justice, these the just judgment of God far exceeds, and has certain other unspeakable grounds for it. Next, since it was indistinct, he says the same thing over again [Romans 3:7]
In this passage the word world means the people who are in this world, just as we read elsewhere that “the whole world is in the power of the evil one.”
It is true that it would not have been just if God had judged the world if its sins were of some benefit to him, so that whenever sinners received forgiveness at his nod, God would appear to be good. Then if they had not sinned, according to this reasoning, he would not appear to be righteous. For if they had not sinned there would be nothing to forgive, and God would not be good. But this kind of thinking is absurd!
[AD 407] John Chrysostom on Romans 3:5-6