In 2 Corinthians 12:2, Paul wrote (apparently about himself)
I know a man in Christ who fourteen years ago was caught up to the third heaven–whether in the body or out of the body I do not know, God knows.
To understand what he meant, we need to know that “heaven” is used in three ways in Jewish cosmology.
- Heaven=atmosphere (“where the birds fly”).
- Heaven=outer space (“where the stars are”).
- Heaven=spiritual realm (“where God lives”)
Paul is referring to the “third heaven” in Jewish cosmology. i.e., where God lives. It is a vision as he makes clear in v1 and v7. So it may not have been a physical thing at all. I think it is something similar to the visions of Ezekiel (ch1 and 10) and Isaiah (ch6) where they had a vision of God’s dwelling place in heaven.