Paul reminds his readers that they were dead in their trespasses and sins, in which they walked following the course of this world and the prince of the power of the air. All of them, Jews included, lived in the desires of the flesh and were by nature children of wrath. But God, being rich in mercy, because of the great love with which he loved us, made us alive together with Christ, raised us up and seated us with him in the heavenly places. By grace they have been saved through faith; this is not their own doing, it is the gift of God, not a result of works, so that no one may boast. They are his workmanship, created in Christ Jesus for good works, which God prepared beforehand so that they would walk in them.
Then Paul invites the Gentiles to remember their former condition: called the uncircumcision by the Jews, they were without Christ, alienated from the commonwealth of Israel and strangers to the covenants of promise, having no hope and without God in the world. Now in Christ Jesus those who once were far off have been brought near by the blood of Christ.
Christ himself is our peace: he made the two peoples one and broke down the dividing wall of hostility, abolishing in his flesh the law of commandments expressed in ordinances, that he might create in himself one new man in place of the two, so making peace. He reconciled both to God in one body through the cross. Through him both have access in one Spirit to the Father.
So the Gentiles are no longer strangers and aliens but fellow citizens with the saints and members of the household of God, built on the foundation of the apostles and prophets, Christ Jesus himself being the cornerstone. In him the whole structure, joined together, grows into a holy temple in the Lord, and they too are being built together into a dwelling place for God by the Spirit.