Paul has just disclosed to the Ephesians the mystery which had been revealed to him, that is, that Jewish and Gentile believers have together been made into new creations in Christ, and as a result, this new work of God, the Church has been formed, so that brothers and sisters in Christ can minister to each other in love.
which in other generations was not made known to people
There is no Old Testament picture of Jews and Gentiles in one body together; rather Israel and the Gentiles remained distinct, though both will enjoy God’s blessing if they believe. The body of believers is an entirely new concept in the NT. This mystery has been revealed to Paul, so that the Church now, at this critical time could understand it. The Gentile believers don’t have to feel like second-class citizens of the Kingdom of Heaven, because they don’t have Abraham, Isaac and Jacob as their forefathers. And, Jewish people don’t have to live under the law, that they couldn’t succeed in keeping anyway. Both are together saved by Grace through Faith in Jesus, and are brothers and sisters together in the Church. And, although it’s Paul’s mission to explain this mystery, he is sharing it with the whole church, so that they, and we, can have the same insight that Paul has. Paul says that this mystery was not made known in other generations, and that it was his mission to reveal it to the gentiles. Col 1:25-27 25 I was made a minister of this church according to the commission from God granted to me for your benefit, so that I might fully carry out the preaching of the word of God, 26 that is, the mystery which had been hidden from the past ages and generations, but now has been revealed to His saints, 27 to whom God willed to make known what the wealth of the glory of this mystery among the Gentiles is, the mystery that is Christ in you, the hope of glory. Previous generations were ignorant of the mystery—it was something that could not be acquired by seeking and finding, but only by revelation from God. Jesus called his disciples blessed to be hearing about the Kingdom of God, and seeing it in their midst as He taught them, saying in Mat 13:16-17 16 But blessed are your eyes, because they see; and your ears, because they hear. 17 For truly I say to you that many prophets and righteous people longed to see what you see, and did not see it, and to hear what you hear, and did not hear it. The mystery was not made known in other generations because only now has it been revealed to his holy apostles and prophets by the Spirit.
3:6. that the Gentiles are fellow heirs, and fellow members of the body.
Heirs together
Jews and Gentiles are “fellow heirs” since God has made both one, made them fellow citizens, given them the same foundation in Jesus, and fitted us all together as stones in the same building, the temple of God.
Members of the body together
We are members of the same body. As 1 Cor 12:12-13 says 12 For just as the body is one and yet has many parts, and all the parts of the body, though they are many, are one body, so also is Christ. 13 For by one Spirit we were all baptized into one body, whether Jews or Greeks, whether slaves or free, and we were all made to drink of one Spirit. Both believing Jews and Gentiles are in the body of Christ, so Gentiles are fellow members of the body with Jews. The Holy Spirit is the same Spirit who works in all of us, and yet works individually with us. We are all put in place in the Church by God to fulfill the role that He has for each of us. All of us have a ministry, and for each of us, our ministry is necessary and important, in fact Critical. As Paul says in 1 Cor 12:14-18 14 For the body is not one part, but many. 15 If the foot says, “Because I am not a hand, I am not a part of the body,” it is not for this reason [n]any less a part of the body. 16 And if the ear says, “Because I am not an eye, I am not a part of the body,” it is not for this reason any less a part of the body. 17 If the whole body were an eye, where would the hearing be? If the whole body were hearing, where would the sense of smell be? 18 But now God has arranged the parts, each one of them in the body, just as He desired. 19 If they were all one part, where would the body be? 20 But now there are many parts, but one body. Each of us, with our individual spiritual gifts to minister to one another, and our individual ministries that God has given us that we can do better than anyone else.
and fellow participants of the promise.
The word for fellow participant is the same word we get symbiotic relationship from. Just as living things with a symbiotic relationship thrive with the other partner in the relationship. In the NT it means “sharing with them, casting one’s lot in with them” or, “fellow participant” or “partner”.
in Christ Jesus through the Gospel.
We are all now, even as Gentiles fully accepted and are fellow participants of the promise of the Messiah Jesus, His salvation by grace through faith, and the indwelling and empowering of the Holy Spirit to live a righteous life. Both believing Gentiles and Jews are under the blessings of the new covenant. If the Old Covenant under Moses had glory, then, as 2 Cor 3:8-11 8 how will the ministry of the Spirit fail to be even more with glory? 9 For if the ministry of condemnation has glory, much more does the ministry of righteousness excel in glory. 10 For indeed what had glory in this case has no glory, because of the glory that surpasses it. 11 For if that which fades away was with glory, much more that which remains is in glory. So, this New Covenant through the atoning sacrifice of Jesus is filled with a perfect glory that never fades away; an eternal relationship with God built on what He has done, not what we have accomplished.
We must be careful to understand, that believing Jews and Gentiles are fellow heirs in Christ, but that does not mean that we are Israel. Peter, addressing Men of Israel, not believers, after the resurrection of Christ in Acts 3:19–21 says 19 Therefore repent and return, so that your sins may be wiped away, in order that times of refreshing may come from the presence of the Lord; 20 and that He may send Jesus, the Christ appointed for you, 21 whom heaven must receive until the period of restoration of all things, about which God spoke by the mouths of His holy prophets from ancient times. The Church is distinct from the nation Israel, but made up of both Jews and Gentiles. Gentiles do not become Jews but rather Jews and Gentiles become “one new person in Christ.” Once the church was established, there are three groups of people—The Church, made up of believing Jews and Gentiles; the Jews who do not believe in Christ and are trying to have a relationship with God through modern rabbinical Judaism, and unbelieving Gentiles—the rest of the world. So Israel and the Church have a lot of distinctions, but Jews and Gentiles within the Church have no distinctions, we have become one in Christ
This mystery of God’s plan of salvation, to found the church on the confession of Jesus as Christ, Savior, Son of God, and Lord was revealed to give God glory, as we begin to appreciate the marvelous wonder of His plan in saving us. (see Rom 16: 25-27). God is the same in the Old and New Testaments, the same Jesus spoken about in all those prophecies is the one who came and died on the cross for our sins. Paul gets to preach, as he says in Rom 1c-4 the gospel of God, 2 which He promised beforehand through His prophets in the holy Scriptures, 3 concerning His Son, who was born of a descendant of David according to the flesh, 4 who was declared the Son of God with power according to the Spirit of holiness by the resurrection from the dead, Jesus Christ our Lord, Jesus came according to the very scriptures that Paul had grown up studying in the Old Testament, and this salvation that he gets to preach was witnessed to and attested to by the Law and the Prophets. Jesus is the foundation of faith for all who believe.