6 But it is not as though the word of God has failed. For not all who are descended from Israel belong to Israel, 7 and not all are children of Abraham because they are his offspring, but “Through Isaac shall your offspring 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 counted as offspring. 9 For this is what the promise said: “About this time next year I will return, and Sarah shall have a son.”
Romans 9:6-9 ESV
Paul brings this response to the likely argument some must have brought forward, saying that since it appeared that many ethnic Jews had rejected Jesus as Messiah, God’s promises to the Jews must have failed. Paul counters this argument by saying, “Not all who are descended from Israel (biologically linked to the man formerly known as Jacob) belong to Israel (the spiritual remnant of the ethnic nation of Israel whom God has chosen to receive salvation through Christ).” This claim would have likely caused some confusion, trying to differentiate between an ethnic Jew of the flesh and a spiritual Jew. All spiritual Jews are ethnic Jews, but not all ethnic Jews are spiritual Jews.
Paul’s letter addresses this earlier in Romans 2:28-29 when Paul declares,
“For no one is a Jew who is merely one outwardly, nor is circumcision outward and physical. 29 But a Jew is one inwardly, and circumcision is a matter of the heart, by the Spirit, not by the letter. His praise is not from man but from God.”
The “outward” sign of being a Jew that Paul addresses at this point in Romans 9 is a biological (flesh) claim to Israel. Many ethnic Israelites would have rested on their ancestry’s laurels to claim that they were to receive the promise of salvation simply based on their biological personhood. Paul uses the example of Abraham’s two sons, Ishmael and Isaac, to refute that flesh is more potent than promise. Both sons were biologically linked to Abraham, yet only Isaac was considered the “child of the promise,” who was considered the spiritual offspring of Abraham. And who determined which of Abraham’s children would spring the offspring of promise? God alone chose this. In the flesh, Abraham would have received Ishmael as his son and even asked God to let him be the blessed one (Genesis 17:18), but it was not Abraham who had the right or authority to decide, but God Himself.
So, what do we conclude from this passage of scripture? All Jews have a claim to Israel in the flesh, but God ultimately decides who will receive the promise of salvation. Jews must be of the flesh AND the promise. There is an additional God-determined qualifier that will determine salvation.