Overview
Even though the word "gospel" is only used four times in the letter to the Ephesians, careful examination of the context indicates
the substance of the the gospel permeates throughout and is comprehensive; not merely a collection of related concepts in which
the message of justification by grace through faith is placed (Eph 2:8-9). In other words, the entire letter is a holistic
explanation of the nature and scope of the gospel. This is clearly evident when comparing Paul's placement and use of the word
"mystery" relative to each other in the letter itself. Paul uses the term three times: The
mystery of his will (Eph 1:9); The mystery of Christ (Eph 3:4-6); and The mystery of the gospel (Eph 6:19). In each case where
the term mystery is used it is implicity/explicidly connected with the gospel.
Mystery of His Will In the first instance the term "mystery" is used, the connection with the gospel is implied. For example, Ephesians 1:9-10 states the "mystery of his will" is to "bring all things in heaven and earth together under one head-Christ Jesus." However, the text coming before (Eph 1:1-8) and the text following Ephesians 1:9-10 (Eph 1:11-3:1) not only presents benefits in Christ, but describes those embracing the gospel by grace through faith as "being raised with Christ" and reackoned in his body under one head through the Holy Spirit made possible by Christ's shed blood and redemptive sacrifice (Eph 2:13-16; cf. 1 Corinthians 12:13). Moreover, it is in the context of explaining this mystery we read "It is by grace you have been saved through faith-and not from yourselves, it is the gift of God-not of works so that no one can boast" (Eph 2:8-9). Compare this with what is written in the sister letter to the Colossians (Col 1:22-23), and with the words of Christ Jesus in John 3:16. On the other hand, those not in union with Christ are nevertheless already positionally, and will ultimately be brought "beneath his feet" through the gospel. This "mystery" was actually declared by recognised prophets coming before first century Jesus and Paul and refers to Genesis 3:15 fulfillment through New Covenant Holy Spirit enablement predicated upon Yeshua's redemptive incarnation (Jeremiah 31, Ezekiel 11:19-20; Ezekiel 36:26-27), death, ressurection and ongoing intercession as High Priest in the order of Melchizedek. Positionally "all things" are already under Yeshua's feet. On the other hand, the Gospel of the Kingdom of God has not been yet been fully realized "on earth as it is in heaven" (cf. Genesis 3:15, Psalm 110:1-4, Ephesians 1:22, Hebrews 2:8, Acts 2:34-35, 1 Corinthians 15:25-26, Romans 16:20). While only Yeshua will ultimately bring all things that remain in opposition under his feet on earth as it is in heaven with his second coming, currently physical and spiritual descendants of Abraham as God followers in Yeshua are to represent the Gospel of the Kingdom of God in their sphere of influence by being ambasadors for Christ abiding in Him. Some practical examples a good pastor would point out include refusing to join in gossipy back-biting discussion, turning a discussion around by speaking life, or even having the backbone to speak up with appropriate correction where needed. Righting wrongs, extending forgiveness, praying and fasting according to kingdom principles (See Isaiah 58) are among many other things that can change the climate in your sphere of influence in partnering with our Lord in bringing a little more under his feet "on earth as it is in heaven." That is why these three mysteries in this letter are sandwiched between Ephesians one (about who Yeshua is as Melchizadek, and who we Already Are in Him) and Ephesians 6 (about appropriating what we have in Him practically on earth in this gospel of the kingdom of God partnership). As a side, it is difficult to untie someone else in an area you are bound in. Walking in greater realms of dominion on earth has a lot to do with having the things in our own lives under the feet of Jesus on earth as it is in heaven first. (Some things we are supernaturally delivered from and other things we have to subdue). Moreover, it is my opinion that Hebrews 6:1-2 is an invintation to move into greater realms of dominion in partnership with the Lord Jesus having subdued all things in our own lives under the Lordship of Yeshua. In any case, it is noteworthy that this mystery is included in Paul's defence of the Gospel in the first letter to the Corinthians (1 Cor 15:1-28), which he shows neccesitates the bodily ressurection of Jesus. In both Ephesians and Corinthians, the supremecy of Christ, and one's position is based upon the gospel. Thus, the gospel is not only the means of reconcilliation with God in union with Christ, but also the means of bringing "all things in heaven and on earth under one head-Christ Jesus."
Mystery of Christ In the second instance the term "mystery" is used, the connection with the gospel is explicit. For example, Ephesians 3:4-7 states the "mystery of Christ" is that both Jews and Gentiles from various backgrounds are not only reconcilled to God as a result of embracing the gospel by grace through faith, but are "members together of one body" forming one new man in union with Christ, or Messiah Yeshua. Those making up the body of Messiah Yeshua'consists of those Jews or Gentiles who are "born from above" by turning away from a lifestyle of sin, accepting Yeshua's substitutionary life, death, and ressurrection on earth for their sin, confessing Yeshua' as Lord, and faithfully following and identifying with him. Paul understood this mystery relative to the Genesis 3:15 declaration in light of the gospel of the kingdom as already present and active but not yet fully realized "on earth as it is in heaven." God said the devil would bruise the heal of the seed of promise until the final consumation, but God also promised that the seed of woman would crush satan's head ultimately in the end of things. To add insult to injury to the devil, God is using mankind who are in Messiah Yeshua and partnering with him to destroy the works of the devil on earth as it already is in heaven by grace through faith right now. That is why Yeshua' commanded the apostles to teach the apostles' disciples to believe, teach, and do "everything" Jesus taught and commanded them (Matthew 28:18). It is also why Paul would say, "the God of peace will soon bruise satan under your feet" (Romans 16:20; cf. Hebrews 2:8). One day there will be no more "bruised heels" among the redeemed of God in Messiah Yeshua! It is noteworthy that this mystery prefeces Paul's declaration of the Gospel in the letter to the Galations (Galatians 3:28-29; 4:4-7). Regarding this mystery, Paul says he became a servant of "this gospel" (Eph 3:7), which does not square with a replacement theology gospel perspective. (See Romans: "Persevering in the Gospel" for more). Subsequently, Paul explains how to live the gospel out out in union with Christ by grace through faith. He does not call for rigid uniformity, rather, unity in the in the gospel with other members in the body of Christ in our roles, relationships and responsibilities through the Holy Spirit. Thus, the gospel is not only the means of reconcilliation with God in union with Christ, but the means/basis for unity with other members of his body. The gospel also entails partnering with God in bringing things under the Gospel of the kingdom rule on earth as it is in heaven in accordance with gospel of the kingdom principles as revealed in the Holy Bible.
Mystery of the Gospel In the last instance the term mystery is used, the connection with the gospel is both implicit and explicit. It is explicit in that Paul uses both terms together where he writes, "Pray also for me that I can fearlessly make known the mystery of the gospel for which I am an ambassador in chains" (Eph 6:19). Paul does not elaborate on what the mystery of the gospel is in the immediate context, but the connection is implicit in light of what had been previously stated regarding the "mystery of his will" (Eph 1:9-10), and the "Mystery of Christ" (Eph 3:4-7). In the latter case Paul says he became a servant of "this gospel" (Eph 3:7), and the latter is prefaced on the former mystery. Moreover, union with Christ is indicitive of unity in his purposes as it pertains to bringing all things in heaven and on earth under one head-Christ Jesus whether in the body or under his feet. Thus the gospel is not only the means of reconcilliation with God in union with Christ through the spirit by grace through faith, but a partnership with God in the ministry of reconcilliation-And, this is the gospel.