Rom 4:16

“It might appear from this that faith is not a free gift of God but that it must first be offered to him by man in order for grace to be given in return. But consider what the apostle teaches about this elsewhere. For when he lists the gifts of the Spirit, which he says are given to believers according to the measure of faith, there among the rest he asserts that the gift of faith is also given. Therefore faith is given by grace.…If the promise rested on works, it would not be guaranteed. But now it is guaranteed because it rests on grace, not on works. I think this can be understood to mean that the things of the law are external to us, but the things of grace are internal … and therefore they have a firmer foundation.”

“You see that it is not the Law only that faith establisheth, but the promise of God also that it will not allow to fall to the ground. But the Law, on the other hand, by being kept to unseasonably, makes even the faith of none effect, and hindereth the promise. By this he shows that faith, so far from being superfluous, is even necessary to that degree, that without it there is no being saved. For the Law worketh wrath, as all have transgressed it. But this doth not even suffer wrath to arise at all: for "where no Law is," he says, "there is no transgression." Do you see how he not only does away with sin after it has existed, but does not even allow it to be produced? And this is why he says "by grace." For what end? Not with a view to their being put to shame, but to the end that the promise might be sure to all the seed. Here he lays down two blessings, both that the things given are sure, and also that they are to all the seed, so gathering in those of the Gentiles, and showing that the Jews are without, if they contend against the faith.”

“Since the law produces wrath, it is said that Abraham was justified and became an heir by faith, so that everything would be by grace. And why is grace necessary? "So that the promise would be firm." For grace, unlike the law, has no transgression, so that what is given would not be uncertain. Since everything comes by grace and the mercy of God, what is given is justly firm "for all of us," that is, for all believers, not only for those who are "of the law," that is, circumcised, but also for those who are uncircumcised, who are the seed of Abraham, born "by faith." Therefore whoever does not have faith is not the seed of Abraham, "who is the father of us all," that is, of believers, as it is written: "I have made you a father of many nations."”

“After showing that the promise made to Abraham and his seed was not to be fulfilled through the law, the Apostle now shows that it is to be fulfilled through faith. In regard to this he does three things: first, he shows through what such a promise is to be fulfilled; second, in whom it is to be fulfilled, at to all the seed; third, by whom it is to be fulfilled, at who quickens the dead. First, therefore, he concludes to his proposition, as it were by division. For it seems necessary that the promise be fulfilled either by faith or by the law; but not by the law, because the promise would be abolished. Hence, he concludes, therefore it is of faith, if we are to attain the promise of being heirs of the world: this is the victory that overcomes the world, our faith (1 John 5:4). Then he confirms this with a middle term contrary to the one he used above. For it was stated that if justice were from the law, the promise would be abolished; but if it be from faith, the promise remains solid in virtue of the power of divine grace justifying man through faith. And that is what he says, that the promise of God might be firm not on actions, which can fall short, but according to grace, which is infallible: my grace is sufficient for you (2 Cor 12:9); for all the promises of God are in him, namely, Christ, i.e., they are true (2 Cor 1:20). Then when he says, to all the seed, he shows in whom this promise is fulfilled. First, he proposes what he intends and says that this promise, which is to be thus fulfilled through faith, is guaranteed by grace to all the seed, i.e., to every man who would be in any way descended from Abraham: their prosperity will remain with their descendants, and their inheritance to their children's children (Sir 44:11). Second, at not to that only, he explains what he meant by all the seed. For there is a bodily descendant: we are the descendants of Abraham (John 8:33), and there is a spiritual descendant: God is able from these stones, i.e., from the gentiles, to raise up children to Abraham (Matt 3:9). Only the bodily descendants of Abraham kept the law, but the spiritual descendants also imitate his faith. Thus, if the promise were solely through the law, it would be fulfilled not in all the descendants but only in the bodily ones. But because it is fulfilled through faith, which is common to all, it is plain that it is fulfilled in all his descendants. Third, at who is the father, he proves something he had presupposed, namely, that the descendants of Abraham are not only the children of the law but also the children of faith. He proves this with a text from Scripture. First, he gives its sense, saying, who, namely, Abraham, is the father of us all, i.e., of all believers, Jew or gentile: that he might be the father of all them that believe (Rom 4:11); look to Abraham, your father (Isa 51:2). Second, he cites the text, saying, as it is written: I have made you a father of many nations (Gen 17:4). Another version has, I have appointed you. But it does not change the sense. Abraham was the great father of a multitude of nations (Sir 44:19).”

“The promise could not be certain to every offspring, that is, to everyone from every nation, unless it was by faith. The source of the promise is faith and not the law, because those who are under the law are guilty, and the promise cannot be given to those who are guilty. For this reason they must first be purified by faith, so that they may become worthy to be called the children of God, so that the promise may be certain. For if they say they are children of God when they are still guilty (that is to say, under the law), then the promise is not certain. First the children of God must be set free from sin. So those who are under the law must be rescued from the law in order to deserve to receive the promise, which is all the greater because it is apart from the law.”