Three chapters of hard argument arrive at the word Paul has been building toward. 25"I do not want you to be unaware of this mystery, brothers." In Paul's vocabulary a mystery is something once hidden and now revealed, too large to have been guessed in advance. 25"a partial hardening has come upon Israel, until the fullness of the Gentiles has come in." The hardening was never the end of the story. It has a boundary built in, the word "until," which promises its own expiration.
Then Paul holds two true things about the same people side by side. 28"they are enemies for your sake," yet 28"they are beloved for the sake of their forefathers." Neither description cancels the other. Israel is an enemy in one respect and beloved in another, and both are accurate at once, because God's relationship to Israel was never reducible to one word.
The sentence that anchors the passage comes next. 29"For the gifts and the calling of God are irrevocable." The word Paul chooses is rare, and he uses it elsewhere only once, where it describes a repentance that leaves no regret behind. It means something close to "without regret," a promise that will never need to be walked back or apologized for. Whatever hardening comes and eventually lifts, God does not regret having called Israel and will not revoke what he gave.
Paul then ties Jew and Gentile together in one sweep. Once you were disobedient and now have received mercy because of their disobedience, and 31"by the mercy shown to you they also may now receive mercy." Disobedience opened the door of mercy for the Gentiles. In its own time the same door will open back toward Israel. Neither group gets there by merit. Both arrive by mercy alone, mercy that seems to have circled through disobedience on purpose.
The whole letter has been drawing careful distinctions, law and grace, works and faith, Jew and Greek. Here they collapse into one plain fact. 32"God has consigned all to disobedience, that he may have mercy on all." Everyone starts in the same condition, and everyone who receives mercy receives it the same way, as a gift no one could argue their way into. That was the mystery Paul unveiled at the start, one wide mercy, large enough to hold Jew and Gentile in the same hand.
Paul adds that 26"all Israel will be saved," and that the Deliverer will come from Zion. Godly readers have differed about what "all Israel" means, and Paul's own emphasis does not depend on settling that. The emphasis lands on God's faithfulness, on a promise that outlasts every hardening, and on a mercy that reaches the people who have never yet deserved it. If you are tempted to write off someone in your life as beyond reach, see how this passage ends. God has shut everyone in together so that he can show mercy to everyone.
Prayer
Father, thank you that your gifts and your calling are things you never take back. Thank you that the mercy you showed us in our disobedience is the same mercy you have promised Israel in theirs. We ask boldly, in keeping with your own irrevocable promise, that the day would come when all Israel is saved, and that until then you would keep us from being wise only in our own sight. In Jesus' name, amen.