Yeah, it gets difficult!
Let's just say I like to use the same words the Bible uses, and I try to make sure I'm using them the same way. So that the wording of Scripture forms my thoughts.
I do much of the same, which is why I often post the Scripture as written, in a different color so no mistake is made between my words and Scripture. But we shouldn't be afraid to paraphrase as long as we stay in the Scripture context. That is one of our teaching tools, because if we truly understand Scripture by The Holy Spirit, then The Holy Spirit will also show us how teach folks at different levels in their education and understanding.
This to me is the strength of your argument, and something I'll need to put more thought into. Very compelling!
So let me ask you this . . .
The central theme of this thead concerns what you've called Israel's birthright promises, is that correct?
And that they have left those whom we think of Israel, and actually belong to those we haven't previously thought of as Israel, am I reading this right? Or do I have the wrong idea?
That's right, partly. There are promises from God that still are to remain among Judah (which I was trying to get you to see in the Gen.49:10 Scripture). And per 1 Kings 11, God promised He'd always leave one tribe in Jerusalem. But David's throne, not there in Jerusalem anymore. The blessing of the best lands, and plenty of corn and wine, not really there either, though it's getting a lot better, just not compared to the lands in the western Christian nations. Same with the most powerful military.
But because the majority of Jews in Jerusalem rejected Christ, He said their house would be left desolate (Matt.23).
Apostle Paul understood this, otherwise he would not have preached this to Gentile believers on Christ Jesus:
Eph 2:11-20
11 Wherefore remember, that ye being in time past Gentiles in the flesh, who are called Uncircumcision by that which is called the Circumcision in the flesh made by hands;
12 That at that time ye were without Christ, being aliens from the commonwealth of Israel, and strangers from the covenants of promise, having no hope, and without God in the world:
13 But now in Christ Jesus ye who sometimes were far off are made nigh by the blood of Christ.
14 For he is our peace, who hath made both one, and hath broken down the middle wall of partition between us;
Why do you think Paul would keep that label "commonwealth of Israel" there applied to believing Gentiles also? It's because that is exactly what God was revealing through His OT prophets about His Kingdom in final. Enlarge the tent God said through Isaiah, to make room for the Gentiles (Isaiah 54). Israel is still going to be a nation in God's future Kingdom, but it's going to be made up mostly of Christ's body of believers that serve Him. Remember what God originally ordained Israel for, i.e., to be a kingdom of priests (Ex.19:6; 1 Pet.2:5; Rev.1:6).
Paul said the same things in Galatians 3 and Romans 4 about the Gentiles inheriting with Abraham because of Faith on Christ Jesus.
In Romans 9, this is also why Paul quoted from Hosea about God having mercy on a people that were not a people (i.e., Gentiles). The prophecies in Hosea were actually written to the ten tribes, and not to Gentiles. Yet Paul quoted Hosea to Gentile Romans. This is why.
Because the ten lost tribes were scattered among the Gentiles, it had to be they and... Gentile believers, that Apostle Paul was preaching these things to. And both... together, would become one body in Christ Jesus.
Rom 4:12-17
12 And the father of circumcision to them who are not of the circumcision only, but who also walk in the steps of that faith of our father Abraham, which he had being yet uncircumcised.
13 For the promise, that he should be the heir of the world, was not to Abraham, or to his seed, through the law, but through the righteousness of faith.
14 For if they which are of the law be heirs, faith is made void, and the promise made of none effect:
15 Because the law worketh wrath: for where no law is, there is no transgression.
16 Therefore it is of faith, that it might be by grace; to the end the promise might be sure to all the seed; not to that only which is of the law, but to that also which is of the faith of Abraham; who is the father of us all,
17 (As it is written, I have made thee a father of many nations,) before Him Whom he believed, even God, Who quickeneth the dead, and calleth those things which be not as though they were.
KJV