John Calvin on Romans 3:29

29. Is he the God of the Jews only? The second proposition is, that this righteousness belongs no more to the Jews than to the Gentiles: and it was a great matter that this point should be urged, in order that a free passage might be made for the kingdom of Christ through the whole world. He does not then ask simply or expressly, whether God was the Creator of the Gentiles, which was admitted without any dispute; but whether he designed to manifest himself as a Savior also to them. As he had put all mankind on a level, and brought them to the same condition, if there be any difference between them, it is from God, not from themselves, who have all things alike: but if it be true that God designs to make all the nations of the earth partakers of his mercy, then salvation, and righteousness, which is necessary for salvation, must be extended to all. Hence under the name, God, is conveyed an intimation of a mutual relationship, which is often mentioned in Scripture, —

“I shall be to you a God, and you shall be to me a people.” (Jeremiah 30:22.)

For the circumstance, that God, for a time, chose for himself a peculiar people, did not make void the origin of mankind, who were all formed after the image of God, and were to be brought up in the world in the hope of a blessed eternity.