Calvin, on Psalm 98:1 (“Sing unto Jehovah a new song, for he hath done marvelous things: his own right hand, and the arm of his holiness, hath gotten him the victory”) and a parallel passage in Isaiah 59:16; characteristically eloquent. What is the righteousness of God? “[T]he illustration of his mercy, grace, and faithfulness”:

In both passages the arm of God stands opposed to ordinary means, which although when employed they derogate nothing from the glory of God, yet prevent us from so fully discovering his presence as we might otherwise do. The language of the Psalmist amounts to a declaration that God would not save the world by means of an ordinary kind, but would come forth himself and show that he was the author of a salvation in every respect so singular. He reasonably infers that mercy of such a wonderful, and, to us, incomprehensible kind, should be celebrated by no ordinary measures of praise. This is brought out still more clearly in the verse which follows, where it is said that his salvation and righteousness are shown to the nations. What could have been less looked for than that light should have arisen upon these dark and benighted places, and that righteousness should have appeared in the habitations of desperate wickedness?…I may add, that the righteousness of God, which is the source of salvation, does not consist in his recompensing men according to their works, but is just the illustration of his mercy, grace, and faithfulness.