If you get to the Interlinear, and click on the number above the Greek words, definitions appear.
It appears in this 2 Thes 2, either a He or the likes of itself, same, etc can be used. So it appears it is more like a system, false teaching or you might say, it has dual meanings.
If you do some serious history checks of the numerous things that various Popes have claimed about themselves, they would certainly fit this man and couple that with their false Father and Son and a creation of a Holy Spirit person out of the Fathers Holy Spirit = hey presto, lawlessness.
Where it uses the word lawless "one" in following verses, NO "one" should even be there.
Logic and common sense tells you, that the opposition will set up and work through Christianity. The wolf in sheep's clothing, angel of light and the power of set seeds, Grossly underestimated.
The Temple here, many think is a prophesy of a 3rd Temple, is rubbish, Paul elsewhere makes it very clear several times that people are now the Temple. That is simply one of the many deceptions thrown out there, more so for the counter reformation, to take ones eyes of satan's throne here on earth. There maybe a 3rd Temple built, to keep this deception alive, but it is Not a prophesy.
