The lie is this: Paul only talks about believers being "one body" in the context of spiritual gifts, never anywhere else.
I was told that in those exact words. That is 100% lie to cover up the bad teaching of the Acts 28 position. The very first time Paul mentions believers being "one body" in any epistle it is talking about the believers partaking of the crucified body of Christ and His shed blood which lines up with Ephesians.
Ephesians 2:16 And that he might reconcile both unto God in one body by the cross, having slain the enmity thereby:
1 Corinthians 10:
 The cup of blessing which we bless, is it not the communion of the blood of Christ? The bread which we break, is it not the communion of the body of Christ?
 For we being many are one bread, and one body: for we are all partakers of that one bread.
Ouch! That's gotta hurt! Notice how after Paul mentions this "one body" he starts contrasting what Israel and the Gentiles do. As you know, there is neither Jew nor Gentile in the "one body".
 Behold Israel after the flesh: are not they which eat of the sacrifices partakers of the alter?
 What say I then? that the idol is any thing, or that which is offered in sacrifice to idols is any thing?
 But I say, that the things which the Gentiles sacrifice, they sacrifice to devils, and not to God: and I would not that ye should have fellowship with devils.
 Ye cannot drink the cup of the Lord, and the cup of devils: ye cannot be partakers of the Lord's table, and of the table of devils.