*1 Cor.12:27; Paul clearly defines the pre - Acts 28 Christians as the Body of Christ.
*Eph.3:6; Paul clearly shows in this narrative that Gentiles "should be fellow heirs
and of the same Body;"
*The significance of 1 Cor. 12:27, and *Eph. 3:6, is that the former was written pre. Acts 28, and the latter post Acts 28. In the former the Jew is first, in the latter the Jew is Lo-Ammi and the Gospel of redemption has been turned to the Gentiles (nations). From the point of view of the title, "the Body of Christ", the two groups are the same, which is further evidence (if it was needed) that the Grace offered to the Ekklesia; (the called out ones for the Body) are one and the same. This also confirms the point of view that the Ekklesia, started at the renting of the Temple veil.
The implications of this for the study of Revelation are profound, and show that the pouring out of the Spirit which started at Pentecost, and ceased at Acts 28; cannot re-commence until those same conditions approximate again on earth, which seem to be or just prior to, or after our Lord's return.
This shows that the groupings of peoples described in the early parts of Revelation (the seven churches etc.) are under a new set of conditions, not those of Acts period or Grace period. The age of Grace is finished, and “works” and “over-coming" are paramount. The "overcomers" are a special group of people with special rewards, and are marked out in Rev. 7:9 as having "white robes", and have suffered greatly (v.14), and their reward and comfort is described in vs. 15-17.
The fact of the Body of Christ being prior to and post Acts 28, and up to an as yet unknown date in the future, not being the same group as the "overcomers"; shows an as yet unknown, but promised linking with the Jewish members (brothers of the Lord).
This linking, or grafting Paul describes in v 17 of Romans 11. The whole of that chapter describes the use of Israel to draw the Nations (Gentiles) and also shows a temporary casting off of Israel "until the fullness of the Gentiles be come in" (v 25). When that has happened Israel shall be saved by Messiah (v.26), because they are the elect people (v.28).
There is therefore a future relationship between the Body (Christ's people), and the Israel of the future described in Revelation, Ezekiel, Zechariah and elsewhere.