He's saying that being a physical descendant of Abraham is not part of the requirement for being part of Spiritual Israel and being "regarded as Abraham's offspring".
He does not argue that point. Remember the context. He is talking about national Israel and in that context he says that the "adoption as sons" belongs to them. Then he asks whether God has broken his promise to them. And in that context he argues that God has always decided salvation on an individual basis. Later, in chapter 11, he will argue that although God decides salvation on an individual basis, he has not rejected national Israel.
Do you see the references to the children of God and children of the promise in Romans 9:6-8 and Galatians 3:26-29? In Romans 9:6-8 the children of God and of the promise are those who are part of Spiritual Israel. So, why can't we use other scripture about the children of God and of the promise to gain further insight into Spiritual Israel? There is no reason why not.
Again, Romans chapters 9 through 11 are focused on national Israel, God's promise to them, and how he intends to keep his promise to them. In that context, since he is focused on national Israel, he discusses what it means to be a child of Jacob. The book of Galatians argues for why Gentiles need not become Jews and that Gentile salvation makes a person a spiritual son of Abraham. Do you see the difference?
In his closing argument in Romans 11, Paul makes the same point using different language. He compares and contrasts natural branches with wild branches. Paul acknowledges that God made the promise of salvation to the natural branches, but also explains that God grants salvation to Gentiles by grafting wild branches onto the vine. The wild olive branches are grafted onto the tree by faith, and the natural branches remain by faith.
That is where I go right because the children of God and children of the promise aren't one thing in Romans 9:6-8 and another thing in Galatians 3:26-29. So, whoever the children of God and of the promise are in Romans 9:6-8, they are the same in Galatians 3:26-29. You have no concept of interpreting scripture with scripture, so that's why you don't understand.
You are making an unexamined assumption by wrongly assigning both groups to "Spiritual Israel." Both groups are children of promise, but that fact alone does not indicate one group. They are united under Christ and share that in common, but they don't have the same history, nor do they share the promise of God in common. The group in Romans 9 are the natural branches because the Adoption of Sons belongs to them. The group in Galatians are the wild branches because they are not part of God's promise to Israel. They are part of God's second promise to Abraham instead. Romans chapters 9 through 11 discuss God's promise to Israel in light of God's first promise to Abraham.
By definition then, Spiritual Israel is comprised of those individuals among Jacob's descendants whom God has chosen for salvation. And God intends to keep his covenant with national Israel as Paul suggests. (Romans 11:15) Someday, national Israel will accept Jesus as Lord and Savior, which will take place when national Israel rises from the dead, so to speak.
So does Romans 9:6-8. You once again are proving that you are not reading the passage carefully.
No. Galatians discusses Abraham's spiritual seed in light of Abraham's physical seed -- Christ. Romans 9 - 11 talks about Abrahams physical seed in light of God's choice.
Again...
Romans 9:6 It is not as though God’s word had failed. For not all who are descended from Israel are Israel. 7 Nor because they are his descendants are they all Abraham’s children. On the contrary, “It is through Isaac that your offspring will be reckoned.” 8 In other words, it is not the children by physical descent who are God’s children, but it is the children of the promise who are regarded as Abraham’s offspring.
Do you see the parts I bolded here? Those all refer to Abraham's spiritual seed/offspring/children. They are the ones who make up Spiritual Israel and are God's children and the children of the promise.
Do you see where Paul says, "not all who are descended from Israel are Israel"? This indicates that Paul has narrowed his focus to descent from Israel. Everything he says from that point forward is narrowly focused on the sons and daughters of Jacob. The Adoption as Sons belongs to them. (Romans 9:4) Paul doesn't intend for his readers to generalize his argument and apply it universally to all. He intends to argue how and why God's promise to THEM will be fulfilled -- a future fulfillment that is invisible to the Amillennial View.
Once again, we can deduce that from Romans 9:6-8 because it indicates that Spiritual Israel is made up of the cihldren of God and of the promise, which Galatians 3:26-29 indicates includes both Jew and Gentile believers.
Romans 9:6-8 is narrowly focused on the physical descendants of Jacob. Galatians 3:26-29 is universally true about anyone who shares the same faith as Abraham.
Then there is this:
Galatians 6:15 Neither circumcision nor uncircumcision means anything; what counts is the new creation. 16 Peace and mercy to all who follow this rule—to the Israel of God.
In this passage Paul equates being part of "the new creation", which has nothing to do with physical things like circumcision, as being part of "the Israel of God". All who follow the rule of being made a new creation in Christ, which has nothing to do with physical things like being circumcised or not, make up the Israel of God.
Translator's notes from the NET Bible:
The word “and” (καί) can be interpreted in two ways: (1) It could be rendered as “also” which would indicate that two distinct groups are in view, namely “all who will behave in accordance with this rule” and “the Israel of God.” Or (2) it could be rendered “even,” which would indicate that “all who behave in accordance with this rule” are “the Israel of God.” In other words, in this latter view, “even” = “that is.”
Your translation expresses the second option. You need to argue why the first option is excluded.
And, yet again, you prove that you are not reading the passage carefully at all.
We are both reading the passage carefully, but you are adding an idea that isn't there in contradiction to the first five verses of Romans 9 and the first line of Romans 9:6. According to Romans 9:4, salvation was promised to Paul's kinsmen. This indicates that in his opinion, physical descent is significant.
No, it does not. Your arguments are extremely weak here. Is this all you have?
Is it the argument that is weak, or the one hearing the argument is unwilling to listen?
You're not understanding that God's promises do apply to them (believers only, of course), but also to Gentile believers as the New Testament teaches repeatedly.
I have noted Paul's use of terminology. Typically, when Paul wants to talk about individuals, he compares Jews to Greeks. And typically when he wants to talk about nations, he compares Israel to Gentiles. In Romans chapters 9 through 11, Paul employs the term Israel. He mentions Jews twice in that context.
The most significant contrast in that context is Romans 10:12, where he says that God is the God of all.
Here below is where Paul begins to alert the reader that he wants to change his focus from the Jews to the Israelites.
Romans 9:3-4
For I could wish that I myself were accursed,
separated from Christ for the sake of my brethren, my kinsmen according to the flesh, 4
who are Israelites, to whom belongs
the adoption as sons . . .
Paul has coined the phrase "the adoption as sons" to indicate salvation. He says that God promised his kinsmen, who are Israelites,
The Adoption as Sons. In this way Paul alerts the reader that he has left the subject of universal salvation to discuss what will happen to the nation born from Jacob. What will God do for the nation of Israel in order to keep his promise to them? That is the issue in those three chapters.
You can only miss that because of doctrinal bias and a lack of spiritual discernment.
You assign motives, which is weak.
Do you not accept that Gentile believers are fellow citizens and fellow heirs with Israelite believers of God's promises as Paul taught in Ephesians 2:11-3:6?
I accept that individual Gentiles and individual Jews who have believed and followed Christ are fellow citizens and fellow heirs with each other. Can you see, though, that Paul has changed his focus from individuals to the nation of Israel in Romans 9?