"Therefore remember that at one time you Gentiles in the flesh, called "the uncircumcision" by what is called the circumcision, which is made in the flesh by hands— remember that you were at that time separated from Christ, alienated from the commonwealth of Israel and strangers to 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." - Eph 2:11-13

"So then you are no longer strangers and aliens, but you are 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 whom the whole structure, being joined together, grows into a holy temple in the Lord. In him you also are being built together into a dwelling place for God by the Spirit." - Ephesians 2:19-22

"When you read this, you can perceive my insight into the mystery of Christ, which was not made known to the sons of men in other generations as it has now been revealed to his holy apostles and prophets by the Spirit. This mystery is that the Gentiles are fellow heirs, members of the same body, and partakers of the promise in Christ Jesus through the gospel." - Ephesians 3:4-6

Paul addresses the Gentiles, highlighting their previous separation and alienation from Israel and the covenants of promise. In Christ, however, the Gentiles become citizens of Israel. The phrase "have been brought near" in Ephesians 2:13 signifies the inclusion and acceptance of Gentiles into the faith community, akin to the conversion process of Jewish proselytes.

The passage emphasizes the reconciliation and unity of Jews and Gentiles through Jesus Christ, asserting that those once far off (Gentiles) have been brought near by Christ's blood. Consequently, Gentiles now share in the same promises, no longer strangers to Israel's commonwealth but citizens of it. Importantly, Jesus Christ is identified as the true Israel, encompassing all who are joined to His body.

Examining key verses:

Ephesians 2:12: Gentiles, once alienated from Israel's commonwealth.
Ephesians 2:19: Gentiles, now no longer strangers and aliens, but you are fellow citizens...

Ephesians 2:12 - Once strangers to the covenants of promise.
Ephesians 3:6 - Now partakers of the promise.

In Christ, Gentiles are now "citizens" of Israel (v. 19), with Jesus as the chief cornerstone. Jesus Christ is the True Israel of God (its fulfillment and foundation), and all united with Him share this identity. Both Old Testament (OT) and New Testament (NT) saints in union with Christ are citizens of Israel.

Gentiles, previously not part of Israel, were excluded from the privileges and promises associated with the Israelite community. Through Jesus Christ, they now have a new relationship with Israel, no longer excluded or deemed outsiders. They are integrated into the faith community, sharing the privileges and promises given to Israel.

In Ephesians 3:4-6, Paul unveils a mystery revealed to him by God: "the mystery of Christ, which was not made known to the sons of men in other generations as it has now been revealed to his holy apostles and prophets by the Spirit. This mystery is that the Gentiles are fellow heirs, members of the same body, and partakers of the promise in Christ Jesus through the gospel."

Which promise do they partake in? The promises given to Israel through Abraham, of course. Did not God promise to Abraham that through him all nations would be blessed? Paul asserts elsewhere (Gal 3:8) that the gospel was preached to Abraham beforehand, meaning that both OT and NT saints were saved by the same grace in Christ and are members of the same body—partakers of the same covenant promises. The difference is simply (if one thinks about it organically) that one group was like a seedling or an immature branch while the other is a fully mature, fruit-bearing tree, yet both are part of the same tree. The former is the original shoot, and the latter is grafted in. The OT saints saw Christ from a distance through promises and shadows, yet in God's plan, those who were regenerate were, even then, united to Christ, part of the same body, and saved by the same blood—the blood to which the temple sacrifices pointed.

"And all these, though commended through their faith, did not receive what was promised, since God had provided something better for us, so that apart from us they would not be made perfect" (Heb 11:39-40).

Just as we can never separate the law from the lawgiver, we likewise cannot separate the benefits from the benefactor. Many in modern-day evangelicalism have wrongly divided the people of God, even while Paul was at pains to show them both in union with Christ. Since Paul stressed the importance of this, let's look afresh at the Scripture beyond our traditions and errors regarding this issue. The text of Scripture is not Israelocentric but Christocentric. Jesus Himself bore witness to this: "You search the Scriptures because you think that in them you have eternal life; and it is they that bear witness about me." (John 5:39)

Here are some objective observations from these passages:

1. Paul acknowledges that the Gentiles were once separate from Israel and its covenants (Ephesians 2:11-12).
2. He explains that through Jesus Christ, the Gentiles who were once far away have been brought near (Ephesians 2:13).
3. Christ is said to have broken down the dividing wall of hostility between Jews and Gentiles (Ephesians 2:14).
4. The purpose of Christ's work was to create one new humanity, reconciling both Jews and Gentiles to God through the cross (Ephesians 2:15-16).
5. Through Christ, both Jews and Gentiles have access to the Father by the same Spirit (Ephesians 2:18).
6. As a result, the Gentiles are no longer strangers and aliens but fellow citizens with the saints and members of the household of God (Ephesians 2:19).
7. The foundation of this household is built on the apostles and prophets, with Christ Jesus as the cornerstone (Ephesians 2:20-21).
8. In Ephesians 3:5-6, Paul refers to the mystery of Christ, which was not known in previous generations but has now been revealed through the Spirit.
9. The mystery is that the Gentiles are fellow heirs with the Jews, members of the same body, and partakers of the promise in Christ Jesus through the gospel (Ephesians 3:6).

These observations reveal that in Ephesians 2:11-21 and 3:5-6, Paul emphasizes the unity and reconciliation between Israel and the Gentiles through Jesus Christ, which was previously a mystery but has now been disclosed.