The revelation of the mystery: BODY OF CHRIST
Ephesians 3:6 KJV
That the Gentiles should be fellow heirs, and of the same body, and partakers of his promise in Christ by the gospel:
Gentiles have become heirs of God and ALL MEMBERS of the same body (Rom 8:17). Just like...
a human body is formed by God, each believer is 'put into' (baptized) Christ's body by one Spirit (Holy Spirit).
1 Corinthians 12:12-13 KJV
For as the body is one, and hath many members, and all the members of that one body, being many, are one body: so also is Christ...
For by one Spirit are we all baptized into one body, whether we be Jews or Gentiles, whether we be bond or free; and have been all made to drink into one Spirit.
And this body is a NEW MAN, made up of Jews and Gentiles, reconciled to peace by the cross...
Ephesians 2:15-16 KJV
Having abolished in his flesh the enmity, even the law of commandments contained in ordinances; for to make in himself of twain one new man, so making peace; [16] And that he might reconcile both unto God in one body by the cross...
having slain the enmity thereby:
..of which Christ Jesus is the HEAD, and this body declared to be the CHURCH
Ephesians 1:22-23 KJV
And hath put all things under his feet, and gave him to be the head over all things to the church, [23] Which is his body,...