That the Gentiles should be fellow heirs, of the same body, and partakers of His promise in Christ through the gospel.
There is no people more envied and hated by as many people as the people of Israel. However, for many others, Israel is a people worthy of admiration. And although for those who do not have knowledge of the Bible, Israel is not seen as a unique people, it does not cease to draw attention to its particular form that distinguishes it from others. The truth is that Israel is a unique people because it was chosen by God to inherit the promise that He made to Abraham. But God’s great love for humanity is so great that He set in motion a plan for the other peoples of the world to be fellow heirs.
Christians should be very careful when they come to relating to the people of Israel. The fact that most Jews have rejected Jesus Christ does not mean that God has substituted His people for us. God is the same yesterday, today and forever, therefore, His promises will never change. Paul puts it this way in Romans 11:28, Concerning the gospel they are enemies for your sake, but concerning the election they are beloved for the sake of the fathers. Israel will be eternally the chosen people of God.
It is necessary to emphasize that we worship the God of Israel, so the Gentiles have been introduced to the worship of the same God worshiped by the children of Abraham, Isaac and Jacob. Ephesians 2:11-13 explains this very clearly, Therefore remember that you, once Gentiles in the flesh—who are called Uncircumcision by what is called the Circumcision made in the flesh by hands—that at that time you 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. But now in Christ Jesus you who once were far off have been brought near by the blood of Christ.
It is clear that by the blood of Christ, the Gentiles have been approached towards Israel and their God. It is not that Israel has been cast aside for us to take their place, but we have been made part of the people of God. Romans 11:17-18 explains it in a very graphic form, And if some of the branches were broken off, and you, being a wild olive tree, were grafted in among them, and with them became a partaker of the root and fatness of the olive tree, do not boast against the branches. But if you do boast, remember that you do not support the root, but the root supports you.
The covenant that God made to Abraham remains intact, Israel continues to be heir of the promise and we have been grafted in that covenant through the blood of Christ. A true Christian does not boast of being the sole heir of the promise, nor does he presume to say that God rejected Israel and placed us in his place. Look what Romans 11:24 says, For if you were cut out of the olive tree which is wild by nature, and were grafted contrary to nature into a cultivated olive tree, how much more will these, who are natural branches, be grafted into their own olive tree?
What we should rejoice is that God has appointed us joint heirs with Israel of the promises given to Abraham. Ephesians 2:19 says, Now, therefore, you are no longer strangers and foreigners, but fellow citizens with the saints and members of the household of God. Let us give thanks to our Lord and King Jesus Christ for our adoption and naturalization. God bless you.