John Calvin Commentary Romans 2:6

"who will render to every man according to his works:" — Romans 2:6 (ASV)

Who will render to every one, etc. Since he had to deal with blind little saints, who thought that the wickedness of their hearts was well covered, provided it was spread over with certain obscure disguises of empty works, he pointed out the true character of the righteousness of works—that is, the kind that is of account before God. He did this so that they would not feel confident that it was enough to appease God if they merely brought words and trifles, or only leaves.

However, this verse does not present as much difficulty as is commonly thought. For the Lord, by visiting the wickedness of the reprobate with just vengeance, will recompense them with what they have deserved. And just as he sanctifies those whom he has previously resolved to glorify, he will also crown their good works, but not on account of any merit. Nor can this be proved from this verse; for although it declares what reward good works are to have, it still by no means shows what they are worth, or what price is due to them. And it is an absurd inference to deduce merit from reward.