Grace: The church is united and holy (2:14-22), and this truth prompts Paul to pray.[1] But before he begins, he first cites his own ministry as an example[2] of this unity. He, a Jew, is in jail for the sake of the Gentiles,[3] and this is no curse, but a privilege! To him, ministry to the Gentiles was "the gift of God's grace" (3:7),[4] an unmerited favor from God. The Creator (3:9) was calling all peoples to draw near to Him through faith in His Son. And Paul was chosen to herald that message to the nations! He didn't deserve this. By the grace of God, he was appointed, and by the power of God, he was enabled for this work (3:7). Paul gets to serve the Gentile elect, the other precious half of God's church.
Mystery: Significant key truths about Christ were kept a "mystery" in prior generations but "now" they were revealed in this age. The recipients of this revelation were New Testament apostles and prophets, but the role to preach and elucidate this message to the Gentiles was given to Paul.[5] And he tells us his insight into this mystery: Gentiles who believe the gospel[6] are fellow heirs, members and partakers with the people of God. In this church age, Gentiles are grafted into the true Israel,[7] fused together as one church. The mystery has been declassified. We now exult in the truth that we are a part of God's people.
[1] What he begins in 3:1 ("For this reason I…"), he resumes in 3:14 ("For this reason I…")—the sentence in 3:1 is incomplete. He resumes his thoughts in 3:14—he intended to pray: "For this reason I bow my knees…"
[2] "If indeed you have heard…" shows his confidence that his audience is aware he is a minister to the Gentiles.
[3] Paul is also "the prisoner of Christ Jesus." He is not jailed because he independently promoted the Gentile cause. No. This was the Lord's idea. Christ called him to this ministry to the Gentiles (Acts 9:15; 26:16-17).
[4] Paul repeats this: "the stewardship of God's grace" (3:2) and "this grace" (3:8). Cf. 1 Cor. 15:10; 2 Cor. 4:1.
[5] Paul also had revelation (3:3), and he was to also preach and illuminate that message for the nations (3:8-9).
[6] This is the sense of "through the gospel." The gospel calls for faith (2:8; Mark 1:15) and regeneration (2:1-5; John 3:3), which are manifested in repentance (Luke 5:32; Acts 26:20).
[7] This refers to regenerate New Covenant Jews in the church age. Cf. Rom. 9:6; 11:1-5; Isaiah 10:21-22.