"And it shall be, in the place where it was declared to them, 'Not My people are you,'" There "they shall be called 'sons of the living God.'"

Paul quotes the famous Hosea prophecy here in Romans chapter 9 and applies it to the nations in that the nations are just as much "not His people" as was Israel in her divorced state from Yahweh. This does not make the nations a fulfillment of the Hosea prophecy, as so many Replacement Theology people and Preterists people think.

Rather, Paul taking a new message to the nations is the latest, greatest EXAMPLE of how God can take a "non-people" and make something of them; after all, He had done it before. He fulfills His promises to Israel in another way, of course, than to the nations, especially as He makes different promises altogether to the nations. But the PRINCIPLE is the same, and this is the principle point.