John Calvin Commentary Romans 11:6

"But if it is by grace, it is no more of works: otherwise grace is no more grace." — Romans 11:6 (ASV)

If through grace, it is no more by works, etc. This amplification is derived from a comparison between things of an opposite character, for such is the case between God’s grace and the merit of works, that whoever establishes the one overturns the other.

But if no regard for works can be admitted in election without obscuring the gratuitous goodness of God, which He designed by this means to be so highly commended to us, what answer can be given to Paul by those infatuated persons, (phrenetici — insane,) who make the cause of election to be that worthiness in us which God has foreseen? For whether you introduce future or past works, this declaration of Paul opposes you, because he says that grace leaves nothing to works.

Paul does not speak here of our reconciliation with God, nor of the means or the proximate causes of our salvation; but he ascends higher, even to this—why God, before the foundation of the world, chose only some and passed by others. And he declares that God was led to make this difference by nothing other than His own good pleasure; for if any place is given to works, he maintains, that much is taken away from grace.

It therefore follows that it is absurd to blend foreknowledge of works with election. For if God chooses some and rejects others, as He has foreseen them to be worthy or unworthy of salvation, then, with the reward of works being established, God's grace cannot reign alone but must be only partly the cause of our election. For as Paul has reasoned before concerning the justification of Abraham, that where reward is paid, there grace is not freely bestowed; so now he draws his argument from the same fountain—that if works are taken into account when God adopts a certain number of people to salvation, reward is a matter of debt and therefore not a free gift.

Now, although Paul speaks here of election, this is a general line of reasoning that he adopts. Therefore, it should be applied to the whole of our salvation.

This helps us understand that whenever it is declared that there are no merits of works, our salvation is ascribed to the grace of God. Or rather, we may believe that the righteousness of works is annihilated whenever grace is mentioned.