Sounds like a
of sloppy assumptions, to me.
Paul repeats what was Christ's first warning regarding His return in Matthew 24, Mark 13 and Luke 21 ... Let no man deceive you by any means: for *that day shall not come,* except there come a falling away first. Does NOT say flying out first it says falling away first, welll who are these that will fall and who are they falling to??... Paul continues and that man of sin (the first sinner) be revealed, the son of perdition, verse 4 identifies who this son of perdition is by virtually quoting Ezekiel 28 as that one who opposeth and exalted himself above all that is called God, or that is worshipped: so that he as God sitteth in the Temple of God, shewing himself that he is God.
You have just been told who the beast or the instead of Jesus is, none other than the devil the first sinner.