Dealing with the fact that so many of his Jewish contemporaries—his fellow Israelites—did not believe Jesus was the Messiah was clearly an emotional struggle for Paul. His pain over their rejection was so deep that he could even wish for God to cut him off if it would mean the salvation of his kinsmen (Rom. 9:3). We should not think, however, that the Jews’ large-scale rejection of Jesus was theologically difficult for the Apostle. As he will argue, it was never the Lord’s purpose to save every descendant of Abraham according to the flesh. “According to the flesh” is the key phrase here, for Paul grounds his argument by distinguishing between two different nations or peoples that bear the name Israel. His basic point is that if God’s word of promise to save Israel (Isa. 45:17) meant that He would save every person of Jewish heritage, the Lord could be charged with failure; however, that is not what the Lord meant when He promised to save Israel, so the Jews’ rejection of Jesus does not mean God has failed. “Not all who are descended from Israel belong to Israel” (Rom. 9:6). Some who have Jewish ancestry do not truly belong to God’s people Israel; therefore, only some who are physical descendants of the patriarchs are true Israelites. It is only this latter group that the Lord promised to save when He pledged to redeem Israel. To prove his point, Paul goes all the way back to Abraham, who was the very first Jew. God would not identify all of Abraham’s children according to the flesh as His own people, but only “the children of the promise” (vv. 7-9). Paul refers specifically to Isaac as the promised child, taking us back to the history of Isaac and Ishmael. The Apostle quotes from Genesis 21, in which God tells Abraham to see Isaac and not Ishmael as the heir promised to the patriarch (see Gen. 15). He also quotes from Genesis 17, which identifies Isaac as the first fulfillment of the Lord’s promise to give Abraham many descendants. Throughout the history of the nation of Israel, those who were Israelites by birth had to be warned again and again that they had no automatic claim on God’s salvation simply for being the physical descendants of Abraham and for possessing blessings such as the temple in Jerusalem (Jer. 7:1-4; Luke 3:1-9). Thus, Paul implies, any expectation that the Lord promised to save everyone of Jewish descent is unfounded. God pledged to save not “all who are descended from Israel” but only those who “belong to Israel.” These who belong to Israel, we shall see, are identified spiritually. They are those who trust in Christ.