Paul tells us that the whole world groans for the revealing of the sons of God. What was his meaning? Why did Paul teach in Romans as he did?
Who is the true Jew?
For he is not a Jew who is one outwardly, nor is circumcision that which is outward in the flesh. But he is a Jew who is one inwardly; and circumcision is that which is of the heart, by the Spirit, not by the letter; and his praise is not from men, but from God. Romans 2:28-29 NASB1995
Just before this verse Paul tells us that Gentiles who possess God’s law in their heart and keep the law represent real circumcision. Paul further informs us that not every son of Abraham is a Jew. He points us to Jacob and Esau. Paul never taught that all men are not sinners, but always pointed us to repentance and God’s resulting gift of this promised new heart, which was a promise made to Israel.
We know that Jacob actually stole Esau’s birthright, but he also wrestled with God to receive that blessing. Men who profess belief but who have not wrestled with God in the inner man likely have not yet passed through the spiritual birth canal.
Paul in keeping with his theme concerning Jews and Gentiles, explains in Romans how that the salvation, which came to us through Israel’s Christ, and which rightfully belongs to them, has been found by us, who are mostly Gentiles but Jews are not excluded. It is just that as an entire people, they are still blinded. We gentiles on the other hand didn’t really steal their birthright, but like Esau most of them did give up their birthright. They did not believe the very Word and it’s promises that gave them this eternal heritage thru this their Christ.
They insisted instead upon unbelief. Their unbelief was not a new thing. They were a stubborn people. Moses experienced it with them in the wilderness. Steven was stoned for reminding them of their own rebellion against God and against His deliverance. Stephen gave them their rebellious history from Abraham thru Moses. Speaking of these times he stated:
Acts 7:38 This is he, that was in the church in the wilderness with the angel which spake to him in the mount Sina, and with our fathers: who received the lively oracles to give unto us: (KJV)
The truth about the church is this: it has always had a rebellious element — even today. When we read of the seven churches in Revelation, there is this element of rebellion within. Without the heart circumcision man is nothing but rebellious toward God, and he remains without wisdom. The wisdom of the world is not God’s wisdom.

Paul concludes his teaching in Romans concerning this body of believers with circumcised hearts, by revealing them to be in God’s olive Tree. The same relationship of Jew and gentile circumcised is shown there. Israel being the natural branches, and we gentiles the unnatural are grafted in until the very last gentile is saved, and; then the remaining of Israel’s nation is added back. We are told by Old Testament prophets that this will occur in a day. Zachariah speaks of that day throughout his book. And we are told by Paul that then all Israel will be saved.
I would suggest to you that his meaning is that with the completion of the Olive tree that Israel the Bride of their Christ is complete. This in no way takes away from the fact that their are mortal men occupying the nations when Jesus and His resurrection bride reign over them. Mortal men will also reside in Israel during this reign of Christ over the earth from that nation. All prophesied events to occur for the nation Israel will see their completion during the future millennium when Christ shall reign. He is coming again to this earth.