Romans 9:6-9
(6) Not as though the word of God hath taken none effect. For they are not all Israel, which are of Israel:
(7) Neither, because they are the seed of Abraham, are they all children: but, In Isaac shall thy seed be called.
(8) That is, They which are the children of the flesh, these are not the children of God: but the children of the promise are counted for the seed.
(9) For this is the word of promise, At this time will I come, and Sara shall have a son.
The failure of the Jews to respond to the gospel of Christ did not mean God’s Word had failed. Instead this rejection was simply the current example of the principle of God’s sovereign choice established in the Old Testament. Paul reminded his readers of a truth he had presented earlier: For not all who are descended from Israel are Israel, that is, spiritual Israel (cf. 2:28-29).
Then Paul gave three Old Testament illustrations of God’s sovereignty (Isaac and Ishmael, 9:7b-9; Jacob and Esau, vv. 10-13; and Pharaoh, vv. 14-18). The first two show that God made a sovereign choice among the physical descendants of Abraham in establishing the spiritual line of promise. Ishmael, born to Hagar (Gen. 16)—and the six sons of Keturah as well (Gen. 25:1-4)—were Abraham’s descendants (sperma), but they were not counted as Abraham’s children (tekna, “born ones”) in the line of promise. Instead, as God told Abraham (Gen. 21:12), It is through Isaac that your offspring will be reckoned (lit., “in Isaac seed [sperma] will be called to you”). Paul repeated the principle for emphasis in different words: It is not the natural children (lit., “the born ones of the flesh”) who are God’s children (tekna, “born ones of God”), but it is the children (tekna) of the promise who are regarded as Abraham’s offspring (sperma). To be a physical descendant of Abraham is not enough; one must be chosen by God (cf. “chosen” in Rom. 8:33) and must believe in Him (4:3, 22-24). God’s assurance that the promise would come through Isaac, not Ishmael, was given to Abraham: At the appointed time I will return, and Sarah will have a son (a somewhat free quotation of Gen. 18:10 from the LXX).
Excerpt from:
Walvoord, J. F., Zuck, R. B., & Dallas Theological Seminary. (1983-c1985). The Bible knowledge commentary : An Exposition of the Scriptures. Wheaton, IL: Victor Books.
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