In 1 Corinthians 5:3-4, Paul writes about being present with the Corinthians when they assemble, albeit, in "spirit".
1 Corinthians 5:3-4 (ESV),
3 For though absent in body, I am present in spirit; and as if present, I have already pronounced judgment on the one who did such a thing. 4 When you are assembled in the name of the Lord Jesus and my spirit is present, with the power of our Lord Jesus...
I realize we have adopted similar language in our time and reference, that is, to be with someone "in spirit", and mean it only metaphorically or symbolically, not literally. But that is how we use it, in our time and reference.
How did Paul mean it, in his time and reference?
We have to remember something about Paul, something Marcus Borg and John Dominic Crossman (among others) brought out, particularly in their book The First Paul: Reclaiming the Radical Visionary Behind the Church's Conservative Icon, namely, that Paul was a "Jewish Christ Mystic" (p. 19).
Paul often had what we would call mystical or ecstatic experiences. They continue:
An ecstatic experience, as the roots of the Greek word suggest, is a nonordinary [sic] state of consciousness. One is "out of" or "beyond" ordinary consciousness and in this state has an overwhelming sense of experiencing God. God becomes an experiential reality. In this sense, mystics know God (emphasis theirs).
It is interesting that they mention the roots of the Greek word ecstasy, because, Biblically, it refers to a "displacement", something an out of body experience dovetails with perfectly.
Here is a partial list of Paul's ecstatic experiences:
Considering this substantial list, not to mention all the other supernatural events that occurred in Paul's life, it is proper to state that Borg's and Crossman's assessment of Paul as a Jewish Christ Mystic is correct.
So, then, should we add out of body experiences to the list, at least for Paul?
I think so, yes. What Paul wrote in 1 Corinthians 5:3-4 is not given to us as a metaphor or symbol. Paul unequivocally stated he was present "in spirit" with the Corinthians, and was able to judge the matter regarding the fornication occurring in the assembly at Corinth. But he writes even more. He orders them to certify their expulsion of the transgressive brother, not only in the name of the Lord Jesus, but also with his spirit present. In some mystical way that we perhaps do not, or even cannot understand in our modern day and age, Paul, through His union with God as a Christ Mystic, was able to be present with the Corinthians when they rendered judgment.
I realize an objection occurs here, that Paul was present with them "in spirit" in the sense that his words and authorization on the action would be with the Corinthians in the form of the letter only, and therefore, no real "out of body" experience took place.
But that to me, is anachronistic eisegesis. We've come, over the centuries, to take for granted the supernatural experiences of the Apostles, and so, have euphemized their words in order to adopt them culturally into our vernacular.
Jesus is our example from the Scriptures. He consistently claimed that His Father was in heaven, and yet, said He was in the Father, and the Father was in Him, all the while present physically upon the Earth (John 14:10). In this sense, Jesus Himself was, so to speak, in two places at once. He was 1.) literally on earth in body and form, but also 2.) in heaven with the Father.
The same with the Christian believer, according to Paul:
Ephesians 2:6 (ESV),
6 and raised us up with him and seated us with him in the heavenly places in Christ Jesus...
Undoubtedly, this is a mystery, and cannot easily be explained or realized, only received and believed.
But, if it is so that Christian believers the world over can literally and physically live and exist upon the Earth, and yet, spiritually, mystically, sit with Christ Jesus in heavenly places, then it is not any harder to believe that Paul could, through the Holy Spirit, "transport", as it were, his spirit supernaturally to other locations, such that he could and did write, that he was present with other people while being hundreds of miles away, and mean it, and it be true.
And, he could also, therefore, have an out of body experience that took him to the "third heaven", where he heard things he wasn't allowed to repeat, which accounts for his "visions and revelations" and the mystery of the gospel, the mystery of the kingdom, which is to say, the mystery of God that is in Christ, that Paul received and could write about, but never fully explain or articulate, hence why he consistently called it a mystery.