At least one Madist claims there are two bodies of believers, one in Christ and the other of Christ.
Paul said there is only one body and one Lord.
The 'Covenantal/Reformed/Calvinistic' concept of the Church= one Church composed of faithers/believers throughout history from Adam onward.
The 'Dispensational' concept of the Church=
Acts 2 Dispensational- The Church/Body of Christ is made up of believers having the indwelling of the Holy Spirit and began at Pentecost, a new dispensation, post cross. Israel is not the Body of Christ/ Church and GOD has separate,distinct purposes and plans for both the BOC and national Israel.
Acts 9 or MAD Dispensational- A new Dispensation began in Acts as national Israel as a whole along with it's leadership rejected their Messiah, began to persecute the Church (Acts 7-8) and Christ from heaven incorporated Paul as His unique Apostle to the nations (Acts 9) and believers were baptized by one Spirit into one body, the BOC, a new creation, the one new man composed of Jew and Gentile without distinction.
Paul does not say that believers from all of human history have been baptized into that body.
The fact that Paul declares that there is one Body does not necessarily mean that GOD did not and does not have a separate plan for a believing remnant of national Israel according to prophecy.
All one has to do is look at prophecy concerning Israel to understand that it has not all been completed yet.....if understood literally.
And when examining prophecy for Israel and comparing it with Paul's words concerning the BOC, it's easy to see that neither the Prophets of Israel nor Paul, the Apostle to the nations, blends the two.
All believers are of the 'household of faith' but not all believers are of prophetic national Israel and not all believers are in the mystery BOC.
Certainly all who are saved in all of history are saved by Christ's work on the cross. That is not to say that believers in all of history have had knowledge of that event.