This man is so expansive, so egotistical about himself that he is the enemy of everything worshipped as god; he sets himself up in the temple of God. Why does he do this? He does it in order to receive the recognition that he feels that he is due. There are several clues here that will help us to identify this person further. The first is that he exalts himself above every "so-called" god. Let's look at what this same apostle said in another place
What we have clarified by Paul's statement there in I Corinthians 8 when compared to II Thessalonians 2:4, is that there is, in reality, only one God. But there are many "so-called" gods—that is, demons or inanimate objects that people worship as gods. The man of sin exalts himself over the true God AND the so-called gods. When this is compared with the last clause, "he sits in the temple of God, showing himself that he is God," there is no other honest conclusion that can be reached but that this is the temple in Jerusalem.
