John Chrysostom
The Apostle did not stop with denial and the words, "By no means." He repeats the same thing affirmatively and says, "God has not rejected His people" (v. 2).
But you will say: this is not proof, but denial. Here, then, is first one proof and then another. The first is when the Apostle declares that he himself is a Jew.
If God had determined to reject the Jews, He would not have chosen Paul from among them. To him He entrusted the whole preaching, the affairs of the whole world, all the mysteries, and the whole divine economy of human salvation.
This is the first argument. The second, which follows it, lies in the words, "His people, whom He foreknew." That is, those whom He clearly knew were capable of receiving faith and would receive it.
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For from among the Jews, three thousand believed, and five thousand, and a great multitude. And lest someone object, "Do you make up the people? If you were called, does it follow that the whole people was called?"
The Apostle added, "God has not rejected His people, whom He foreknew." He speaks as though saying: with me there are three thousand, five thousand, and a great multitude.
What then? Does the seed likened to the multitude of the stars of heaven and the sand of the sea consist in three thousand, five thousand, and a great multitude?
Are you not plainly deceiving and misleading us, when you present yourself and the few with you as the whole people? Are you not deluding us with empty hopes by saying that the promise has been fulfilled?
For all have perished, and salvation has fallen to the lot of a few. This is boasting and arrogance, and we will not tolerate such false conclusions.
But so that the Jews could not say this, see what answer the Apostle gives in the following words. He does not state the objection, but anticipates it, and gives the solution from Old Testament history.
What is this solution? "Do you not know," he says, "what the Scripture says in the account of Elijah?"