I have evidence the body and the church are the same as Paul clearly says:
Col. 1:18
He is also head of the body, the church;
I would suggest that Gentiles were added to Israel, not physical Israel but to Israel God’s people:
In Romans Paul shows the Jews are “natural” branches of a cultivated olive tree with a holy root and how the Gentiles are “wild” branches and were grafted
IN among them.
Rom. 11:16
If the first piece of dough is holy, the lump is also; and if the root is holy, the branches are too. 17 But if some of the branches were broken off, and you, being a wild olive, were grafted in among them and became partaker with them of the rich root of the olive tree,
In the OT Gentiles were excluded from Israel:
Eph. 2:12
remember that you were at that time separate from Christ, excluded from the commonwealth of Israel, and strangers to the covenants of promise, having no hope and without God in the world.
They were separated from Israel but
now have been brought near:
13
But now in Christ Jesus you who formerly were far off have been brought near by the blood of Christ.
Jews and Gentiles are now in one body, through the
cross and Christ’s
blood:
16
and might reconcile them both in one body to God through the cross,
Jesus purchased the church with his blood, here Paul is talking to the elders at Ephesus:
Acts 20:28
… the Holy Spirit has made you overseers, to shepherd the church of God which He purchased with His own blood.
Through Jesus’ D,B&R both Jew and Gentile are now in one body. Just as in the OT there were two groups of people, Jews(God’s people) and Gentiles(not God’s people), after the cross there are now two new groups of people, Christians and non-Christians. Anyone outside of Christ is lost and has no hope and are without God.
We must look at things spiritually and not physically. It’s not fleshly descendants of Abraham who are true Israel but the children of promise.
Rom. 9:6...
For they are not all Israel who are descended from Israel; 7 nor are they all children because they are Abraham's descendants, but: "through Isaac your descendants will be named." 8 That is, it is not the children of the flesh who are children of God, but the children of the promise are regarded as descendants.
Christians are the children of promise.
Gal. 4:28
And you brethren, like Isaac, are children of promise.
Paul shows that Christians are God’s people and heirs of the promise by saying we spiritually meet the physical requirements of an OT Israelite.
Col. 2:11
and in Him you were also circumcised with a circumcision made without hands, in the removal of the body of the flesh by the circumcision of Christ;
Gal. 3:29
And if you belong to Christ, then you are Abraham's descendants, heirs according to promise.
Phil. 3:2
Beware of the dogs, beware of the evil workers, beware of the false circumcision; 3 for we are the circumcision, who worship in the Spirit of God and glory in Christ Jesus and put no confidence in the flesh,
Are you willing to argue that no one is baptized into the Body of Christ by the Holy Spirit during this dispensation?
Yes, we when we are water baptized IN THE NAME OF JESUS, we are added to the body.
Acts 2:41
So then, those who had received his word were baptized; and that day there were added about three thousand souls.