6 But it is not that the word of God has taken no effect. For they are not all Israel who are of Israel, 7 nor are they all children because they are the seed of Abraham; but, “In Isaac your seed shall be called.” 8 That is, those who are the children of the flesh, these are not the children of God; but the children of the promise are counted as the seed. (Romans 9:6–8, NKJV)
God showed His faithfulness by fulfilling His promise to Abraham that “in your seed all the nations of the earth shall be blessed” (Gen. 22:18). The gospel of Christ reveals this promised blessing as salvation from sins “for everyone who believes, for the Jew first, and also for the Greek” (Rom. 1:16). The gospel also makes it clear the “children of the promise” are now the children of God. The promised blessing is obtained in Jesus Christ, not as a Jew under the Law of Moses (Gal. 3:16-19). Whether Jew or Gentile, “we are all sons of God through faith in Christ Jesus,” not through the Law of Moses (Gal. 3:23-27). The nation of Israel is no longer God’s chosen people. God chose us “in Christ” for redemption, regardless of race (Eph. 1:4; 2 Thess. 2:13). In Christ, “there is neither Jew nor Greek, there is neither slave nor free, there is neither male nor female; for you are all one in Christ Jesus” (Gal. 3:28). Being a citizen of the nation of Israel does not make one a child of God. The church is now the “Israel of God” (Gal. 6:15-16).