Romans 9 – Israel – chosen ones in Old Testament. vs. 6 “For they are not all Israel who are descendants from Israel.” vs.15 “I will have mercy on whom I have mercy, and I will have compassion on whom I have compassion.” vs.16 “So then it does not depend on the man who wills or the man who runs, but on God who has mercy.”
Each man has a free will to chose God, but unless God gives repentance, no man will turn to God. God knows who will turn to him and will give his grace to that person. This is election and predestination. That is why we preach the gospel to whosoever will choose God, because only God knows who will serve him. vs.23 “And he did so in order that he might make known the riches of his glory upon vessels of mercy, which he prepared beforehand for glory.”
Israel was given the law to show them and the world they were sinners and separated from God. But they wouldn’t believe God and they stumbled over the stumbling stone laid in Zion.