Eph 3:6 This mystery is that the Gentiles are fellow heirs (a), members of the same body (b), and partakers of the promise in Christ Jesus through the gospel (c).
The mystery as we continue is not something we can’t comprehend. It is but the hidden wisdom of God uncovered in the gospel, just as the mystery of the Godhead, in Christ was the Godhead in bodily form, “For in Him dwells all the fullness of the Godhead bodily” (Col 2:9)
This mystery further reveals that Jesus did not send eternal life, He is the eternal life. 1Jn 5:12 “He who has the Son has life; he who does not have the Son of God does not have life.”
We are created or recreated in Christ crafted by God for a purpose. 2Cor 4:7 “But we have this treasure in jars of clay, to show that the surpassing power belongs to God and not to us.” In these jars of clay, He as in Zacchaeus has invited Himself to our lives and filled these jars of clay for His purposes. We are “created in Christ Jesus for every good works.” Good works do not grant salvation, they are meant to validate our salvation, they are the light in display. Christ, in all His aspects is Himself “the mystery of godliness.”
The effect of this mystery is displayed in three points in Eph 3:6. Point #1 The Gentiles are fellow heirs with God and joint heirs with Christ through adoption (Rom 8:14-17, Rom 3:28-30, Gal 3:27-29, Eph 2:12-13). Jesus was the first to break the barrier to reach the Samaritans (Gentiles) preaching the good news to them first with the woman at the well. “This was the Lord’s doing; It is marvelous in our eyes” (Psa 118:23).