Commenting on John 6: 29, Calvin writes:
But we may think it strange that God approves of nothing but faith alone; for the love of our neighbor ought not to be despised, and the other exercises of religion do not lose their place and honor. So then, though faith may hold the highest rank, still other works are not superfluous. The reply is easy; for faith does not exclude either the love of our neighbor or any other good work, because it contains them all within itself. Faith is called the only work of God, because by means of it we possess Christ, and thus become the sons of God, so that he governs us by his Spirit. So then, because Christ does not separate faith from its fruits, we need not wonder if he make it to be the first and the last.
I think it’s also very interesting that he qualifies what sort of work faith is. Calvin’s argument against the role of works in justification is against the Papist concept of merit. Here he says merit is not involved. I think this is a huge point that needs to be clarified when we are arguing about the nature of justification. If we can’t understand our relationship to God without merit we will either become antinomians or legalists.