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.”
How does Israel now fit into the divine plan? Compassion for his fellow Israelites must have driven Paul to seek the mind of God for an answer. Led by the Spirit as he searched the books of Moses and the writings of the prophets, Paul gained the insight he needed, which he now shares with the believers in Rome and with us.
Far from having abandoned Israel, God by his sovereign mercy has carved out a remnant within Israel—people Paul calls “the children of the promise”—who are Abraham’s true, spiritual, and righteous offspring. Membership in this remnant is not a birthright but can only be gained through faith in Jesus Christ. And because “what counts is grace, not race” (N. T. Wright’s phrase cited by Douglas Moo), membership is open to both Jews and Gentiles.
This, then, is the overall theme of chapters 9–11, and these four verses, by distinguishing ethnic Israel from spiritual Israel, introduce the theme. To launch his argument, Paul highlights two significant promises God made to Abraham about the birth of Isaac. Paul’s astute interpretation of those promises proves that God’s word has not failed.
Paul’s argument is complicated and therefore is a challenge to express clearly in few words. By persevering through this exposition, you will be rewarded with a deeper understanding of Paul’s use of OT Scripture to teach new covenant truth. And you may be surprised by how much of that truth he communicates by a single word, once again the important verb “to reckon.”An election within an election
Paul’s statement in verse 6 that “not all who are descended from Israel belong to Israel” is a bit awkward, but this is how he distinguishes the totality of Israelites from the subset of those who benefit from God’s promise. Only the remnant consisting of those who have been faithful to God as now expressed by belief in Christ can be considered to truly “belong to Israel.”
This does not mean that God has walked away from his calling of Israel as his chosen nation. All Israelites, including those who reject Jesus as their Messiah, continue to be God’s people. This is clear from the opening verses of this chapter. And in 11:28–29 Paul emphasizes once again the status Israel enjoys in regard to God’s election. Although they are enemies of the gospel, “they are beloved for the sake of their forefathers. For the gifts and the calling of God are irrevocable.”
Those who physically descend from Israel (Jacob) are elect in one sense, and those few who have found salvation through Christ are elect in another sense. So Paul describes an Israel within Israel—an election of the faithful within an election of the nation. Some refer to this righteous remnant as “the Church hidden in Israel.”God appoints Isaac to be the child of the promise
Paul’s first piece of evidence for his argument is a quotation from Genesis 21:12. You can read that chapter for the circumstances of Sarah’s conflict with Hagar, the servant who had given birth to Abraham’s first son. When Sarah asked Abraham to send away Hagar and Ishmael, Abraham was deeply grieved. At this point God told Abraham to do as Sarah requested. The reason God gave is quoted by Paul in verse 7: “Through Isaac shall your offspring be named.”
In verse 8 Paul cites this declaration by God to distinguish between “the children of the flesh” (Ishmael and his descendants) and “the children of God” (Isaac and his descendants). God continued to care for Ishmael and blessed him materially, but Isaac was the child of the promise.Not human merit, but God’s sovereign grace
God chose Isaac not because he was a better person than Ishmael but only because he was the appointed channel through whom God would bless his people. In other words, God’s naming of Isaac owed solely to God’s sovereign grace. And Paul wants us to know that this is how God’s election continues to operate. As Moo points out, “God’s words to Abraham in Gen. 21:12, according to Paul, imply a principle according to which God acts in bestowing his covenantal blessings.”
This is the principle that Paul applies to the subset of Israel—actually the subset of all people, Jews and Gentiles—who obtain God’s blessings only by grace through faith in Christ.
God’s grace imparts faith, which opens the door to the promise. And because it is faith, not bloodline, that gains access to the promise, all people of all races, including Ishmael’s physical descendants, can become children of God through belief in God’s Son (see 4:16). Quite clearly the phrase “children of God” points back to 8:16 as a reference to Christians. Although Paul is content in these verses to imply this vital truth, he will make it explicit as the chapters unfold.God’s reckoning of his spiritual offspring
Paul gives a telltale signal of this truth in verse 8. It is the verb “are reckoned” (logizomai), which ESV translates “are counted.” Because the believers in Rome knew the meaning of this word, they were much more likely to discern Paul’s intent in this passage than are modern readers. (One of my goals in this exposition is to draw attention to logizomai, as I have done in chapter 4 and 6:11.)
The Roman believers would have recalled Paul’s prior use of logizomai in reference to Genesis 15:6 where God reckoned Abraham righteous in response to his faith (see 4:1–3). Joseph Fitzmyer points out that the verb is “expressive of the divine freedom of election. God chose to reckon Abraham as upright; now he chooses to reckon the children of Abraham born of the promise as the real offspring of Abraham.”Divine enablement of the promise
In verse 9 Paul adds a critical feature concerning God’s promise of the birth of Isaac. Here is what God told Abraham: “About this time next year I will return, and Sarah shall have a son” (Genesis 18:10). At this promise Abraham and Sarah laughed unbelievingly, because Abraham was 100 and Sarah was 90 (Genesis 17:17). He was impotent and she was barren.
But when God makes a promise he commits to its fulfillment. What was impossible naturally became possible supernaturally, and the couple was able to conceive a child.
With this quote, Paul clinches his argument that people become the children of God not through natural means, as was the case with Ishmael, but only through God’s election and enablement. His grace and power—without them we are doomed, with them we soar as the children of God.