Believer's Works Esteemed Righteous by God's Grace

"A more fruitful result follows; because, when God regenerates his elect, he

inscribes a law on their hearts and in their inward parts, as we have elsewhere seen, and shall see again in the thirty-sixth chapter. (Jeremiah 31:33; Ezekiel 36:26, 27.) But the difficulty is not yet solved; because the faithful, even if regenerated by God's Spirit, endeavor to conform themselves to God's law, yet, through their own weakness, never arrive at that point, and so are never righteous: I answer, although the righteousness of works is mutilated in the sons of God, yet it is acknowledged as perfect, since, by not imputing their sins to them, he proves what is his own. Hence it happens, that although the faithful fall back, wander, and sometimes fall, yet they may be called observers of the law, and walkers in the commandments of God, and observers of his righteousness. But this arises from gratuitous imputation, and hence also its reward. The works of the faithful are not without reward, because they please God, and pleasing God, they are sure of remuneration. We see, then, how these things are rightly united, that no one obeys the law, and that no one is worthy of the fruits of righteousness, and yet that God, of his own liberality, acknowledges as just those who aspire to righteousness, and repay them with a reward of which they are unworthy. When, therefore, we say that the faithful are esteemed just even in their deeds, this is not stated as a cause of their salvation, and we must diligently notice that the cause of salvation is excluded from this doctrine; for, when we discuss the cause, we must look nowhere else but to the mercy of God, and there we must stop. But although works tend in no way to the cause of justification, yet, when the elect sons of God were justified freely by faith, at the same time their works are esteemed righteous by the same gratuitous liberality." 

John Calvin, Commentary on Ezekiel 18:17