John Calvin on Romans 15:11

11. Praise God, all ye Gentiles, etc. This passage is not inaptly applied; for how can they, who know not God’s greatness, praise him? They could no more do this than to call on his name, when unknown. It is then a prophecy most suitable to prove the calling of the Gentiles; and this appears still more evident from the reason which is there added; for he bids them to give thanks for God’s truth and mercy. (Psalm 117:1.)