Paul asks whether God has rejected his people and answers by no means: he himself is an Israelite, a descendant of Abraham, of the tribe of Benjamin. He recalls Elijah, who thought he was alone and to whom God said he had kept seven thousand who had not bowed the knee to Baal. So too now there is a remnant chosen by grace, and if it is by grace it is no longer by works. What Israel sought it did not obtain, but the elect did; the rest were hardened, as the Scriptures say.
Paul asks whether they stumbled so as to fall beyond recovery and answers no: through their trespass salvation has come to the Gentiles, to make Israel jealous. If their failure means riches for the world, how much more their full inclusion! Paul, an apostle to the Gentiles, magnifies his ministry in the hope of making his fellow Jews jealous and saving some. If the firstfruits are holy, so is the whole lump.
With the image of the olive tree, he explains that some branches were broken off and the Gentiles, as branches of a wild olive, were grafted in among the others to share the richness of the root. They must not boast over the branches, for they do not support the root, but the root supports them. They must consider the kindness and severity of God; if they do not continue in his kindness, they too will be cut off, and the natural branches, if they do not continue in unbelief, will be grafted in again.
Paul reveals a mystery: a partial hardening has come upon Israel until the fullness of the Gentiles has come in, and in this way all Israel will be saved. The gifts and the calling of God are irrevocable. God has consigned all to disobedience, that he may have mercy on all. The chapter ends with a doxology: oh, the depth of the riches and wisdom and knowledge of God! For from him and through him and to him are all things. To him be glory forever. Amen.