For this cause. Paul's imprisonment, which ought to have been held as a confirmation of his apostleship, was undoubtedly presented by his adversaries in an opposite light. He therefore points out to the Ephesians that his chains served to prove and to declare his calling; and that the only reason why he had been imprisoned was, that he had preached the gospel to the Gentiles. His unshaken firmness was no small additional proof that he had discharged his office in a proper manner. The prisoner of Jesus Christ. [1] To strengthen his authority still more, he speaks in lofty terms of his prison. In the presence of the world and of wicked men, this might have appeared to be foolish boasting; but, in addressing godly persons, it was a dignified and faithful manner. The glory of Christ not only overcomes the ignominy of the chains, but converts what was in itself a reproach into the highest honor. If he had merely said, "I am a prisoner," this would not have conveyed the idea of his being an ambassador. Imprisonment alone has no claim to this honor, being usually the mark of wickedness and crime. But the crowns and sceptres of kings, to say nothing of the imposing splendor of an ambassador, are less honorable than the chains of a prisoner of Jesus Christ. Men might think otherwise, but it is our duty to judge of the reasons. So highly ought the name of Christ to be revered by us, that what men consider to be the greatest reproach, ought to be viewed by us as the greatest honour. For you Gentiles. Another circumstance greatly fitted to interest the Ephesians was, that the persecutions of Paul were endured for the Gentiles, -- that his troubles and dangers were on their account.

Footnotes

1 - "Know that for no other reason am I, Paul, loaded with these chains. It was for no evil action, but for the love which I bear to the Lord Jesus Christ." -- Erasmus.

For this cause - On account of preaching this doctrine; that is, the doctrine that the gospel was to be proclaimed to the Gentiles.
I Paul, the prisoner of Jesus Christ - A prisoner in the service of the Lord Jesus; or made a prisoner in his cause. Not a prisoner for crime or debt, or as a captive in war, but a captive in the service of the Redeemer. This proves that at the time of writing this, Paul was in bonds, and there can he no question that he was in Rome. This would be more correctly rendered, "For this cause I, Paul, am the prisoner," etc. So Tyndale renders it, "For this cause I, Paul, the servant of Jesus, am in bonds." So also Locke, Rosenmuller, Doddridge, Whitby, Koppe, and others understand it. By this construction the abruptness now manifest in our common version is avoided.
For you Gentiles - Made a prisoner at Rome on your behalf, because I maintained that the gospel was to be preached to the Gentiles; see Acts 22:21-23. He was taken first to Cesarea, and then to Rome. The cause of his imprisonment and of all his difficulties was, that he maintained that the gospel was to be preached to the Gentiles; that when the Jews rejected it God rejected them; and that he was specially called to carry the message of salvation to the pagan world.

For this cause - Because he maintained that the Gentiles were admitted to all the privileges of the Jews, and all the blessings of the new covenant, without being obliged to submit to circumcision, the Jews persecuted him, and caused him to be imprisoned, first at Caesarea, where he was obliged to appeal to the Roman emperor, in consequence of which he was sent prisoner to Rome. See Acts 21:21-28, etc.
The prisoner of Jesus Christ for you Gentiles - For preaching the Gospel to the Gentiles, and showing that they were not bound by the law of Moses, and yet were called to be fellow citizens with the saints; for this very cause the Jews persecuted him unto bonds, and conspired his death.

For (1) this cause I Paul, (a) the prisoner of Jesus Christ for you Gentiles,
(1) He maintains his apostleship against the offence of the cross, upon which he also makes an argument to confirm himself, affirming that he was not only appointed an apostle by the mercy of God, but was also appointed particularly to the Gentiles. And this was to call them everywhere to salvation, because God had so determined this from the beginning, although he deferred a great while the manifestation of his counsel.
(a) These words, "the prisoner of Jesus Christ", are taken passively, that is to say, "I, Paul, am cast into prison for maintaining the glory of Christ."

For this cause I Paul, the prisoner of Jesus Christ,.... Not actively, whom Christ had apprehended by his grace, and made a prisoner of hope; but passively, who was made a prisoner for Christ, on account of preaching Christ, and his Gospel: he was not a prisoner for any capital crime, as theft, murder, &c. and therefore be was not ashamed of his bonds, but rather glories in them; and a prison has often been the portion of the best of men in this world: from hence we learn, that this epistle was written when the apostle was a prisoner at Rome; and the consideration of this his condition serves much to confirm the truths he had before delivered, seeing they were such as he could, and did suffer for; and which must engage the attention of the Ephesians to them, and especially since his sufferings were on their account:
for you Gentiles: because he preached the Gospel to the Gentiles, which the Jews forbid, that they might not be saved; and because he taught them, that circumcision and the rest of the ceremonies of the law were not binding upon them; which gave great offence to the Jews, who were the means of bringing of him into these circumstances, and particularly the Asiatic Jews, the Jews of Ephesus; who having seen and heard him there, knew him again when in the temple at Jerusalem, and raised a mob upon him, having bore a grudge against him for his ministry at Ephesus, by which means he became a prisoner; so that he might truly say, he was a prisoner for the sake of them; see Acts 21:27. One of Stevens's copies adds, "am an ambassador", as in Ephesians 6:20 and another of them, "glory", or "rejoice"; see Philippians 2:16.

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.

HIS APOSTOLIC OFFICE TO MAKE KNOWN THE MYSTERY OF CHRIST REVEALED BY THE SPIRIT: PRAYER THAT BY THE SAME SPIRIT THEY MAY COMPREHEND THE VAST LOVE OF CHRIST: DOXOLOGY ENDING THIS DIVISION OF THE EPISTLE. (Ephesians. 3:1-21)
of Jesus Christ--Greek, "Christ Jesus." The office is the prominent thought in the latter arrangement; the person, in the former. He here marks the Messiahship of "Christ," maintained by him as the origin of his being a "prisoner," owing to the jealousy of the Jews being roused at his preaching it to the Gentiles. His very bonds were profitable to ("for" or "in behalf of you") Gentiles (Ephesians 3:13; 2-Timothy 2:10). He digresses at "For this cause," and does not complete the sentence which he had intended, until Ephesians 3:14, where he resumes the words, "For this cause," namely, because I know this your call of God as Gentiles (Ephesians 2:11-22), to be "fellow-heirs" with the Jews (Ephesians 3:6), "I bow my knees to" the Father of our common Saviour (Ephesians 3:14-15) to confirm you in the faith by His Spirit. "I Paul," expresses the agent employed by the Spirit to enlighten them, after he had been first enlightened himself by the same Spirit (Ephesians 3:3-5, Ephesians 3:9).

For this cause. This refers to the glorious work of the cross in "making peace and bringing the Gentiles nigh," described in chapter 2.
I, Paul. The verb of which "I, Paul," is the subject, is not given until Ephesians 3:14 is reached. The intervening verses are parenthetic. At Ephesians 3:14 Paul repeats the first clause of Ephesians 3:1, and then gives the verb.
The prisoner of Jesus Christ. A prisoner at Rome when this was written, on account of the gospel of Jesus Christ.
For you Gentiles. It was the hatred of the Jews towards him, on account of his apostleship to the Gentiles, which caused his seizure. See Acts 21:33, and Acts 28:17, Acts 28:20.

For this cause - That ye may be so "built together," I am a prisoner for you gentiles - For your advantage, and for asserting your right to these blessings. This it was which so enraged the Jews against him.