John Chrysostom

"Not as though the word of God had taken none effect." To show that he had courage to bear all these things for the word of God, that is, the promise made to Abraham. For as Moses seemed to be pleading for the Jews, yet was doing everything for God's glory (for he says, "Lest they say, Because He was not able to save them, He led them forth to destroy them in the wilderness"; stay Thy wrath), so also does Paul, That they may not say (he means) that the promise of God has fallen to the ground, and He has disappointed us of that. …

Homily on Romans 16 ↗

Theophylact of Ohrid

I, he says, am inflamed by the fact that God is blasphemed, and therefore expressed the desire that all be saved. But if not all are saved, it does not follow from this that God lied in the promises given to the fathers, and that His word did not come true. He fulfilled what was promised, even though the blasphemers say that He promised to some and gave to others.

Commentary on Romans ↗

Thomas Aquinas

After asserting the greatness of the Jews, the Apostle now shows that it did not refer to those who descended according to the flesh from the ancient patriarchs but to the spiritual progeny chosen by God. First, he shows that this greatness arises from God's selection; second, that this selection applies generally to Jew and gentiles, at even us, whom also he has called (Rom 9:24). …

Commentary on Romans ↗