Hereupon the question is immediately raised, has God then rejected His people? To this chapter 11 is the answer. The apostle gives three proofs that it is by no means the case. Firstly, he is himself an Israelite; there is a remnant whom God has reserved, as in the days of Elias-a proof of the constant favour of the Lord, of the interest He takes in His people, even when they are unfaithful; so that when the prophet, the most faithful and energetic among them, knew not where to find one who was true to God besides himself, God had His eyes upon the remnant who had not bowed the knee to Baal. Secondly, the call of the Gentiles, and their substitution for Israel, was not the definitive rejection of the latter in the counsels of God; for God had done it to provoke Israel to jealousy. It was not, then, for their rejection. Thirdly, the Lord would come forth out of Sion. and turn away the iniquities of Jacob.
That which the apostle, or rather which the Holy Ghost, says on this point requires to be looked at in more detail.
The apostle, in quoting the case of Elias, shews that when Israel was in such a state that even Elias pleaded against them, yet God had not rejected them, He had reserved for Himself seven thousand men. This was the election of sovereign grace. It was the same thing now. But it was by grace, and not by works. The election then, has obtained the blessing, and the rest was blinded. Even as it was written, "God hath given them the spirit of slumber," etc.
Had they then stumbled that they should fall? No! But through their fall salvation is come to the Gentiles to provoke Israel to jealousy-a second proof that it was not for their rejection. But if their diminishing and fall was a blessing to the Gentiles, what should not the fruit be of their restoration? If the first-fruits are holy, so is the lump; if the root, the tree also. Now, as to the continued chain of those who enjoy the promises in this world, Abraham was the root, and not the Gentiles; Israel, the natural stock and branches. And here is that which happened in the good olive-tree of promise in this world, of which Abraham was the root (God Himself the source of leaf and fruit), and Israel the stem and the tree. There had been some bad branches, and they had been cut off; and others from the Gentiles grafted in, in their place, who thus enjoyed the richness natural to the tree of promise. But it was on the principle of faith that they, being of the wild olive-tree, had been grafted in. Many of the Israelite branches, the natural heirs of the promises, had been cut off because of their unbelief; for when the fulfilment of the promises was offered them, they rejected it. They rested on their own righteousness, and despised the goodness of God. Thus the Gentiles, made partakers of the promises, stood on the principle of faith. But if they abandoned this principle, they should lose their place in the tree of promise, even as the unbelieving Jews had lost theirs. Goodness was to be their portion in this dispensation of God's government, with regard to those who had part in the enjoyment of His promises, if they continued in this goodness; if not, cutting off. This had happened to the Jews; it should be the same with the Gentiles if they did not continue in that goodness. Such is the government of God, with regard to that which stood as His tree on the earth. But there was a positive counsel of God accomplished in that which took place, namely, the partial blinding of Israel (for they were not rejected) until all the Gentiles who were to have part in the blessing of these days should have come in. After this Israel should be saved as a whole; it should not be individuals spared and added to the assembly, in which Israel had no longer any place as a nation; they should be saved as a whole, as Israel. Christ shall come forth from Sion as the seat of His power, and shall turn away iniquity from Jacob, God pardoning them all transgressions.
This is the third proof that Israel was not rejected. For while enemies, as concerning the gospel at the present time, they are still beloved for the fathers' sakes. For that which God has once chosen and called He never casts off. He does not repent of His counsels, nor of the call which gives them effect. But if the counsel of God remains unchangeable, the way in which it is accomplished brings out the marvellous wisdom of God. The Gentiles had long continued in the disobedience of unbelief. God comes in in grace. The Jews opposed themselves to the actings of grace. They lose all right to the promises through this unbelief, so that they must receive the effect of the promise on the footing of pure mercy and the sovereign grace of God,  in the same way as the poor Gentile. For He had shut them all up in unbelief, that it might be pure mercy to all. Therefore it is that the apostle exclaims, O depth of wisdom and knowledge! The promises are fulfilled, and the pretension to human righteousness annihilated; the Jews who have lost everything receive all on the true ground of the goodness of God. Their apparent loss of all is but the means of their receiving all from sovereign grace, instead of having it by virtue of human righteousness, or an unforfeited promise. All is grace: yet God is ever faithful, and that in spite of man's unfaithfulness. Man is blessed; the Jew receives the effect of the promise; but both the one and the other have to attribute it to the pure mercy of God. There is nothing about the assembly here: it is the tree of promise, and those who in virtue of their position have part successively in the enjoyment of the promises of earth. The unbelieving Jews were never cut off from the church, they were never in it. They had been in the position of natural heirs of the right to the promises. The assembly is not the Jews' own olive-tree according to nature, so that they should be grafted into it again. Nothing can be plainer: the chain of those who had a right to the promises from Abraham was Israel; some of the branches were then cut off. The tree of promise remains on the earth: the Gentiles are grafted into it in place of the Jews, they also become unfaithful (that is to say, the case is supposed), and they would in their turn be cut off, and the Jews be reinstated in the old olive-tree, according to the promises and in order to enjoy them; but it is in pure mercy. It is clearly not by the gospel they get the blessing; for, as touching the gospel, they are enemies for the Gentiles' sake; as touching election, beloved for the fathers' sake.
Remark further here an important principle: the enjoyment of privileges by position makes us responsible for them, without saying the individual was born again. The Jewish branch was in the tree of promise and broken off: so the Gentiles. There was nothing vital or real; but they were in the place of blessing, "partakers of the root and fatness of the olive tree," by being grafted in.
These communications of the mind of God end this portion of the book, namely, that in which the apostle reconciles sovereign grace shewn to sinners (putting all on a level in the common ruin of sin) with the especial privileges of the people of Israel, founded on the faithfulness of God. They had lost everything as to right. God would fulfil His promises in grace and by mercy.