John Calvin Commentary Matthew 12:37

"For by thy words thou shalt be justified, and by thy words thou shalt be condemned." — Matthew 12:37 (ASV)

By your words you will be justified. This was a common proverb, which He applied to the present subject. For I have no doubt that this was a saying which the people frequently had in their mouths: “Every man is condemned or acquitted by his own acknowledgment.” But Christ turns it to a somewhat different meaning: that a wicked speech, being the indication of concealed malice, is enough to condemn a man.

The attempt which the Papists make to torture this passage, so as to set aside the righteousness of faith, is childish. A man is justified by his words, not because his speech is the ground of his justification (for we obtain by faith the favor of God, so that He reckons us to be righteous persons), but because pure speech¹⁴² absolves us in such a manner that we are not condemned as wicked persons by our tongue. Is it not absurd to infer from this that men deserve a single drop of righteousness in the sight of God?

On the contrary, this passage upholds our doctrine. For, although Christ does not here treat of the ground of our justification, yet the contrast between the two words points out the meaning of the word justify. The Papists reckon it absurd in us to say that a man is justified by faith, because they explain the word justified to mean that he becomes, and is, actually righteous. We, however, understand it to mean that he is accounted righteous and is acquitted before the tribunal of God, as is evident from numerous passages of Scripture. And is not the same thing confirmed by Christ when He draws a contrast between justified and condemned?

¹⁴² “La parole pure, droite, et honneste;” — “pure, upright, and becoming speech.”;” — “pure, upright, and becoming speech.”