3:1-7 For having preached the doctrine of truth, the apostle was a prisoner, but a prisoner of Jesus Christ; the object of special protection and care, while thus suffering for him. All the gracious offers of the gospel, and the joyful tidings it contains, come from the rich grace of God; it is the great means by which the Spirit works grace in the souls of men. The mystery, is that secret, hidden purpose of salvation through Christ. This was not so fully and clearly shown in the ages before Christ, as unto the prophets of the New Testament. This was the great truth made known to the apostle, that God would call the Gentiles to salvation by faith in Christ. An effectual working of Divine power attends the gifts of Divine grace. As God appointed Paul to the office, so he qualified him for it.
6. Translate, "That the Gentiles are," &c. "and fellow members of the same body, and fellow partakers of the (so the oldest manuscripts read, not 'His') promise, in Christ Jesus (added in the oldest manuscripts), through the Gospel." It is "in Christ Jesus" that they are made "fellow heirs" in the inheritance of God: "of the same body" under the Head, Christ Jesus; and "fellow partakers of the promise" in the communion of THE Holy Spirit (Eph 1:13; Heb 6:4). The Trinity is thus alluded to, as often elsewhere in this Epistle (Eph 2:19, 20, 22).