Romans 9:27

After he had, through that wisdom of God which Paul speaks among the perfect, set forth the secret and hidden things of the divine dispensation, and had shown by what reasoning and in what order God either displays his wrath in the vessels of wrath or the riches of his glory in the vessels of mercy; and had taught that each one becomes a vessel of wrath from this, that by his own hardness and impenitent heart he treasures up for himself wrath in the day of wrath, while the vessels of mercy are those who have cleansed themselves from these things and have prepared themselves for every good work — now, in order to confirm these very things with greater authority, he teaches that they were prescribed also in the prophets: "Isaiah," he says, "cries out on behalf of Israel: If the number of the children of Israel be as the sand of the sea, a remnant shall be saved." For the prophet, foreseeing things to come, saw that very many of Israel — and especially those who are compared to the sand of the sea — would through their own hardness and impenitent heart be "vessels of wrath fitted for destruction," not believing in their own life, but crucifying the Lord of majesty. "If therefore," he says, "they be as the sand of the sea, a remnant shall be saved." Those who are not saved are as the sand of the sea; but the remnant which shall be saved are as the stars of heaven. For the word of the promise which was made to Abraham contains both: "Your seed," he says, "shall be as the sand of the sea, and as the stars of heaven."

But Isaiah cries out for Israel. This is what he says, that Isaiah cries out for those who believe in Christ (Isaiah 10:22). For these are truly Israelites, as the Lord says to Nathanael: Behold, truly an Israelite, in whom there is no deceit (John …

This shows that the Lord is the cornerstone, uniting both walls in himself. Hosea's testimony is spoken of the Gentiles, but the Lord unites both Jews and Gentiles, according to what he said in the gospel about the latter: "I have other sheep that are not of this fold; I must bring them also and they will heed my voice. So there shall be one flock, one shepherd."

If by remnant … we are to understand not election of the justified to eternal life but election of those who are to be justified, that kind of election is truly hidden and cannot be known by us, who must regard all men as parts of a single lump of clay. If some claim to be able to know it, I must confess my own weakness in this matter.

"For Esaias," he says, "crieth concerning Israel." That is, speaks out boldly, and uses no dissimulation. Why then lay a charge against us, when they afore declared the same thing with more than trumpet's loudness? And what does Isaiah cry? "Though the number of the children of Israel be as the sand of the sea, a remnant shall be saved." Do you see that he too does not say that all are to be saved, but that those that are worthy shall? For I regard not the multitude, he means, nor does a race diffused so far distress me, but those only do I save that yield themselves worthy of it. And he does not mention the "sand of the sea" without a reason, but to remind them of the ancient promise whereof they had made themselves unworthy. Why then are you troubled, as though the promise had failed, when all the Prophets show that it is not all that are to be saved?