Charles Ellicott Commentary Romans 3:5

"But if our righteousness commendeth the righteousness of God, what shall we say? Is God unrighteous who visiteth with wrath? (I speak after the manner of men.)" — Romans 3:5 (ASV)

But if our unrighteousness.—A new and profound question suggests itself to the mind of the Apostle, and his keen intellect will not let it go: “If the sin (here the unbelief) of man only tends to vindicate (commends or establishes) the righteousness of God, why should that sin be punished?” The mere raising of such a question requires an apology; it is only as one human might speak about another human that he dares to express such a thought.

That, too, is an impossible objection, for if it were valid, there could not be any judgment. No sin would be punishable, for all sin would serve to emphasize the strict veracity of God in His denunciations of it, and therefore would ultimately contribute to His glory. It would thus cease to be sinful, and there would be nothing to hinder us from adopting the principle that is so slanderously attributed to us—that it is lawful to do evil that good may come. A slander it is, and any such principle with all that pertains to it—i.e., with the whole of the preceding argument—is justly condemned.