4 They are Israelites, and to them belong the sonship, the glory, the covenants, the giving of the law, the worship, and the promises; 5 to them belong the patriarchs, and of their race, according to the flesh, is the Christ. God who is over all be blessed for ever. Amen.
6 But it is not as though the word of God had failed. For not all who are descended from Israel belong to Israel, 7 and not all are children of Abraham because they are his descendants; but "Through Isaac shall your descendants be named." 8 This means that it is not the children of the flesh who are the children of God, but the children of the promise are reckoned as descendants.
Matthew Henry's Commentary on Romans 9:4-8
Commentary on Romans 9:1-5
(Read Romans 9:1-5)
Being about to discuss the rejection of the Jews and the calling of the Gentiles, and to show that the whole agrees with the sovereign electing love of God, the apostle expresses strongly his affection for his people. He solemnly appeals to Christ; and his conscience, enlightened and directed by the Holy Spirit, bore witness to his sincerity. He would submit to be treated as "accursed," to be disgraced, crucified; and even for a time be in the deepest horror and distress; if he could rescue his nation from the destruction about to come upon them for their obstinate unbelief. To be insensible to the eternal condition of our fellow-creatures, is contrary both to the love required by the law, and the mercy of the gospel. They had long been professed worshippers of Jehovah. The law, and the national covenant which was grounded thereon, belonged to them. The temple worship was typical of salvation by the Messiah, and the means of communion with God. All the promises concerning Christ and his salvation were given to them. He is not only over all, as Mediator, but he is God blessed for ever.
Commentary on Romans 9:6-13
(Read Romans 9:6-13)
The rejection of the Jews by the gospel dispensation, did not break God's promise to the patriarchs. The promises and threatenings shall be fulfilled. Grace does not run in the blood; nor are saving benefits always found with outward church privileges. Not only some of Abraham's seed were chosen, and others not, but God therein wrought according to the counsel of his own will. God foresaw both Esau and Jacob as born in sin, by nature children of wrath even as others. If left to themselves they would have continued in sin through life; but for wise and holy reasons, not made known to us, he purposed to change Jacob's heart, and to leave Esau to his perverseness. This instance of Esau and Jacob throws light upon the Divine conduct to the fallen race of man. The whole Scripture shows the difference between the professed Christian and the real believer. Outward privileges are bestowed on many who are not the children of God. There is, however, full encouragement to diligent use of the means of grace which God has appointed.