John Calvin Commentary Romans 4:5

"But to him that worketh not, but believeth on him that justifieth the ungodly, his faith is reckoned for righteousness." — Romans 4:5 (ASV)

But believes on him, etc. This is a very important sentence, in which he expresses the substance and nature both of faith and of righteousness. He indeed clearly shows that faith brings us righteousness, not because it is a meritorious act, but because it obtains for us the favor of God.

Nor does he declare only that God is the giver of righteousness, but he also arraigns us of unrighteousness, so that the bounty of God may come to aid our need. In short, no one will seek the righteousness of faith except the one who feels that he is ungodly. For this sentence is to be applied to what is said in this passage—that faith adorns us with the righteousness of another, which it seeks as a gift from God. And here again, God is said to justify us when he freely forgives sinners and favors with his love those with whom he might justly be angry, that is, when his mercy obliterates our unrighteousness.