John Calvin Commentary Genesis 22:15

"And the angel of Jehovah called unto Abraham a second time out of heaven," — Genesis 22:15 (ASV)

And the angel of the Lord called unto Abraham. What God had promised to Abraham before Isaac was born, He now again confirms and ratifies, after Isaac was restored to life and arose from the altar—as if it had been from the sepulcher—to achieve a more complete triumph.

The angel speaks in the person of God, so that, as we have said before, the embassy of those who bear His name may have greater authority by their being clothed with His majesty. However, these two things are thought to be hardly consistent with each other: that what was previously gratuitously promised should here be deemed a reward.

For we know that grace and reward are incompatible. Now, however, since the blessing which is promised in the seed contains the hope of salvation, it may seem to follow that eternal life is given in return for good works. And the Papists boldly seize upon this and similar passages to prove that works are deserving of all the good things which God confers upon us.

But I most readily turn this subtle argument back on those who advance it. For if that promise, which is now ascribed to a reward, was previously gratuitous, it appears that whatever God grants to good works ought to be received as from grace. Certainly, before Isaac was born, this same promise had already been given, and now it receives nothing more than confirmation.

If Abraham deserved such great compensation on account of his own virtue, the grace of God, which anticipated him, will be of no effect. Therefore, so that the truth of God, founded upon His gratuitous kindness, may stand firm, we must necessarily conclude that what is freely given is nevertheless called the reward of works.

Not that God would obscure the glory of His goodness, or in any way diminish it, but only that He may motivate His own people to the love of doing good when they perceive that their acts of duty are so pleasing to Him as to obtain a reward; while He nevertheless pays nothing as a debt, but gives to His own benefits the title of a reward.

And in this there is no inconsistency. For the Lord here shows Himself doubly liberal, in that He, wishing to stimulate us to holy living, transfers to our works what properly belongs to His pure beneficence. The Papists, therefore, wrongfully distort those gracious invitations of God—by which He would correct our sluggishness—to a different purpose, so that man may arrogate to his own merits what is the mere gift of divine liberality.