The Old Testament makes a clear distinction between Israel, God’s people, and the rest of humankind (the Gentiles). Jesus as Messiah brings an end to what separated Jews from Gentiles – the Law. We all are saved and united to God in Christ, not through the Law.
For He [Jesus] Himself is our peace, who has made both one, and has broken down the middle wall of separation, having abolished in His flesh the enmity, that is, the law of commandments contained in ordinances, so as to create in Himself one new man from the two, thus making peace, and that He might reconcile them both to God in one body through the cross, thereby putting to death the enmity. And He came and preached peace to you who were afar off and to those who were near. For through Him we both have access by one Spirit to the Father. Now, therefore, you are no longer strangers and foreigners, but fellow citizens with the saints and members of the household of God, having been built on the foundation of the apostles and prophets, Jesus Christ Himself being the chief cornerstone, in whom the whole building, being fitted together, grows into a holy temple in the Lord, in whom you also are being built together for a dwelling place of God in the Spirit. (Ephesians 2:14-22)
St Paul in Romans 11:24-32 offers a different metaphor of grafting branches to describe the same reality of salvation mentioned above. All people, both Jew and Gentile, are saved together as one people. Christ has brought an end to the dividing wall that separated Jews from Gentiles and forms them into one human race. Paul tells the Romans:
For if you have been cut from what is by nature a wild olive tree, and grafted, contrary to nature, into a cultivated olive tree, how much more will these natural branches be grafted back into their own olive tree. Lest you be wise in your own conceits, I want you to understand this mystery, brethren: a hardening has come upon part of Israel, until the full number of the Gentiles come in, and so all Israel will be saved; as it is written, “The Deliverer will come from Zion, he will banish ungodliness from Jacob”; “and this will be my covenant with them when I take away their sins.” As regards the gospel they are enemies of God, for your sake; but as regards election they are beloved for the sake of their forefathers. For the gifts and the call of God are irrevocable. Just as you were once disobedient to God but now have received mercy because of their disobedience, so they have now been disobedient in order that by the mercy shown to you they also may receive mercy. For God has consigned all men to disobedience, that he may have mercy upon all.
Fraternized 