Ephesians 3:1 For this reason I, Paul, the prisoner of Christ Jesus for you Gentiles
The postscript to the letter to the Ephesians indicates it was written while Paul was imprisoned in Rome. His imprisonment stemmed from the action taken by the Jews as a result of Paul preaching to the Gentiles and in particular his fellowship with an Ephesian brother.
Acts 21:29 (For they had previously seen Trophimus the Ephesian with him in the city, whom they supposed that Paul had brought into the temple.)
Ephesians 3:2 if indeed you have heard of the dispensation of the grace of God which was given to me for you,
Christ commissioned Paul to preach to the gentiles.
Acts 22:21 "Then He said to me, ‘Depart, for I will send you far from here to the Gentiles.’"
Ephesians 3:3 how that by revelation He made known to me the mystery (as I have briefly written already,
Paul was given the gospel by direct revelation from Christ, his gospel was independent of the other apostles.
Galatians 1:11 But I make known to you, brethren, that the gospel which was preached by me is not according to man. 12 For I neither received it from man, nor was I taught it, but it came through the revelation of Jesus Christ.
Ephesians 3:4 by which, when you read, you may understand my knowledge in the mystery of Christ),
This indicates that he had given them this information briefly in a previous letter.
Ephesians 3:5 which in other ages was not made known to the sons of men, as it has now been revealed by the Spirit to His holy apostles and prophets: 6 that the Gentiles should be fellow heirs, of the same body, and partakers of His promise in Christ through the gospel,
It was certainly promised to Abraham that in his offspring all nations would be blessed, but how it would come about was not revealed until Christ came.
Genesis 22:18 "In your seed all the nations of the earth shall be blessed,
Romans 1:16 For I am not ashamed of the gospel of Christ, for it is the power of God to salvation for everyone who believes, for the Jew first and also for the Greek.
Ephesians 2:13 But now in Christ Jesus you who once were far off have been brought near by the blood of Christ.14 For He Himself is our peace, who has made both one, and has broken down the middle wall of separation,
Ephesians 3:7 of which I became a minister according to the gift of the grace of God given to me by the effective working of His power.
Paul was made a full apostle by Christ and endowed with the Holy Spirit so that he was equal to the other apostles in knowledge and power.
2 Corinthians 12:11 I have become a fool in boasting; you have compelled me. For I ought to have been commended by you; for in nothing was I behind the most eminent apostles, though I am nothing.
Ephesians 3:8 To me, who am less than the least of all the saints, this grace was given, that I should preach among the Gentiles the unsearchable riches of Christ,
Grace is the giving of something undeserved. Paul had persecuted the followers of Christ and he never forgot it.
1 Corinthians 15:9 For I am the least of the apostles, who am not worthy to be called an apostle, because I persecuted the church of God.10 But by the grace of God I am what I am, and His grace toward me was not in vain; but I labored more abundantly than they all, yet not I, but the grace of God which was with me.
Ephesians 3:9 and to make all see what is the fellowship of the mystery, which from the beginning of the ages has been hidden in God who created all things through Jesus Christ;
It is not to be supposed that Paul is saying that Christ did the work of the original creation. Rather he is referring to the spiritual creation of the new heaven and earth which God has promised.
Jeremiah 4:23 I beheld the earth, and indeed it was without form, and void; And the heavens, they had no light.
This is speaking of the spiritual state of God’s people prior to Christ’s ministry.
Isaiah 65:17 For, behold, I create new heavens and a new earth: and the former shall not be remembered, nor come into mind.
This is not the physical replacement of the heavens and earth; it is the creation of a new order of things in the existing heaven and earth; this creation is by the work and gospel of Jesus Christ.
Isaiah 51:16 And I have put My words in your mouth; I have covered you with the shadow of My hand, That I may plant the heavens, Lay the foundations of the earth, And say to Zion, ‘You are My people.’"
2 Peter 3:13 Nevertheless we, according to His promise, look for new heavens and a new earth in which righteousness dwells.
Ephesians 3:10 to the intent that now the manifold wisdom of God might be made known by the church to the principalities and powers in the heavenly places,
The Gospel is to be preached to all men, even those in positions of power in this world; the very authorities that Christ is made higher than by his exaltation to the right hand of God. The Roman Government itself would be changed by the preaching of the Gospel, as will all governments when Christ returns.
Ephesians 1:21 far above all principality and power and might and dominion, and every name that is named, not only in this age but also in that which is to come.
Matthew 28:18 And Jesus came and spoke to them, saying, "All authority has been given to Me in heaven and on earth.
Ephesians 3:11 according to the eternal purpose which He accomplished in Christ Jesus our Lord,
Christ has been the cornerstone of the purpose of God right from creation, without his submittal to his father’s will it could not have been accomplished.
1 Peter 1:20 He indeed was foreordained (foreknown – not ‘in existence’) before the foundation of the world, but was manifest in these last times for you
Ephesians 3:12 in whom we have boldness and access with confidence through faith in Him.
Those who have believed and been baptised into Christ can have confidence in approaching God through Christ.
Hebrews 4:14 Seeing then that we have a great High Priest who has passed through the heavens, Jesus the Son of God, let us hold fast our confession.
15 For we do not have a High Priest who cannot sympathize with our weaknesses, but was in all points tempted as we are, yet without sin.
16 Let us therefore come boldly to the throne of grace, that we may obtain mercy and find grace to help in time of need.
Ephesians 3:13 Therefore I ask that you do not lose heart at my tribulations for you, which is your glory.
Tribulations are part of a life in Christ; suffering on his behalf was something all should value.
Acts 5:41 So they departed from the presence of the council, rejoicing that they were counted worthy to suffer shame for His name.
Christ suffered because of the love that he had for us; this love we should glory in.
Paul was suffering for the love that he had for the Ephesian brethren; they should see it in this way, glory in his love and not be downhearted.
There is a great principle being demonstrated.
2 Timothy 2:10 Therefore I endure all things for the sake of the elect, that they also may obtain the salvation which is in Christ Jesus with eternal glory. 11 This is a faithful saying: For if we died with Him, We shall also live with Him.
I hope this is helpful,