John Calvin Commentary Romans 3:19

"Now we know that what things soever the law saith, it speaketh to them that are under the law; that every mouth may be stopped, and all the world may be brought under the judgment of God:" — Romans 3:19 (ASV)

Now we know, etc. Leaving the Gentiles, he distinctly addresses his words to the Jews. He had a much more difficult work in subduing them because, although no less destitute of true righteousness than the Gentiles, they covered themselves with the cloak of God’s covenant, as if being separated from the rest of the world by God's election was sufficient holiness for them.

And he indeed mentions those evasions which he well understood the Jews were ready to bring forward. For whatever was said in the law unfavorably of humanity, they usually applied to the Gentiles, as if they were exempt from the common condition of humankind; and no doubt they would have been so, if they had not fallen from their own dignity.

Hence, so that no false confidence in their own worthiness should be a hindrance to them, and that they might not limit to the Gentiles alone what applied to them in common with others, Paul here anticipates them. He shows, from what Scripture declares, that they were not only counted among the multitude, but that condemnation was specifically pronounced upon them.

And we indeed see the Apostle's discretion in undertaking to refute these objections. For to whom had the law been given but to the Jews, and for whose instruction but theirs should it have served? What it then states about others is, so to speak, accidental—or as they say, παρεργον, an appendage—but its teaching applies mainly to its own disciples.

Regarding under the law, he says that the Jews were those for whom the law was destined; it therefore follows that it especially concerns them. By the word "law," he also includes the Prophets, and so the whole of the Old Testament—that every mouth may be stopped, etc.; that is, that every evasion may be cut off, and every occasion for excuse.

It is a metaphor taken from courts of law, where the accused, if he has anything to plead as a lawful defense, requests permission to speak, so that he might clear himself of the charges against him. But if he is convicted by his own conscience, he is silent and, without saying a word, waits for his condemnation, having already been condemned by his own silence.

This saying in Job 40:4 has the same meaning: I will lay my hand on my mouth. He indeed says that although he was not entirely without some kind of excuse, he would nevertheless stop justifying himself and submit to God's sentence.

The next clause contains the explanation: for his mouth is stopped who is so firmly held by the sentence of condemnation that he cannot possibly escape. According to another sense, to be silent before the Lord is to tremble at His majesty and to stand mute, astonished at His brightness.