2 Thess 2 contains a cryptic reference to a "man of lawlessness" and something or someone that is "restraining".
First to be noted is that the section appears to some to have been styled after typical jewish and early Christian apocalyptic scenario wherein an epic and protracted struggle of the Messiah (Christ) and his archnemesis (AntiChrist), including the idea that the AntiChrist figure would have a brief period of success in leading men away then to be crushed in a final decisive battle. It is suggested from the wording (and dissimilar style) found in 2 Thess 2 that the author was drawing from some such pre-existing apocalyse now lost to us.
Just what the writer intended to convey with his reference to a "restraining thing" (as usually translated) in verse 6 and "he who is restraining now" in verse 7 has been a subject of much discussion. Very early intepretations felt the restraining power and restrainer were references to the Roman empire and emperor because of their stabilizing influence upon radical elements. Yet because the Roman empire is no longer here so moderns attempting to decifer the passage have suggested the Holy Spirit or perhaps Jesus is the "restrainer". Others like the WT interpret the influence of Paul as the implied restraint. They of course identify the "man of lawlessness" as Christendom and not any political or eschatological type entity. Just whether the author meant to identify any particular person as the "man of lawlessness" is hard to say, but the language is very similar to that elsewhere applied to the antichrist figure Antiochus, and so it is possible he had somone in mind but since the description seems part of the typical motif is is just as likely that he was simply using the language in a less historical, prophetic way.
Anyway, the point under discussion in 2 Thess 2 is timing. A sequence of events would necessarily preceed the promised return of Jesus. Below is a literal translation of the verses 6b-10a:
"And now the thing retraining you know, for to be revealed him in the time of him. For the mystery already works of lawlessness, only he restraining him now, until out of midst it comes. And then will be revealed the lawless one, whom the Lord will consume by the spirit of the mouth of him and bring to nothing by the appearance of the coming of him of whom is the coming according to working within of satan in all power and to signs and to wonders of a lie and with all deceipt of unrighteousness in those being lost...."
Given the context and apparent motive for the chapter it sems to me that the revealing of the man of lawlessness was deemed yet future but imminent (contrary to many commentaries) and that directly subsequent was to be his undoing by the Lord. This precludes the WT spin and interpretation that the "restraint" was Paul or other apostles. Of course it is possible that that was the intent but this would be unlikely if critical scholarship is correct in dating the book to about 50 years after Paul's death. If we assume otherwise and Paul was the author and his intent was to say that he was a 'restraint' then he was mistaken is saying that the Lord would respond with violence to the subsequent 'revealing' after his departing. If we understand the Greek words katechon (what is restraining) and katechon (one who restrains) as they are generally translated we have no idea what the author was saying.
But what if the Greek words are differently translated as "the seizing power" and "the seizer" as suggested by some commentaries (though with different interpretation than I here will propose)?
Here's what I propose:
Verse 6 opens with the statement that they "now know' the thing seizing power and follows in 7 by saying the "mystery of lawlessness is already at work" (ie. they are in the age when these developements are occuring). The verses immediatly prior to 6 introduce 'the man of lawlessness' concept for the first time. This seems to flow. That is, they now know about this man of lawlessness because the author has just spoke of him and the apocalyptic scenerio. With this interpretation, the "thing seizing" is the man of lawlessness and his attempt to dethrone god (vss 3-5). Verse 7 continues by saying the lawlessness would continue till the man of lawlessness is taken out of the way.
I know no Greek and so welcome open minded scholarly consideration of this suggestion here proposed. I feel it would eliminate the eternal question of what the author meant by "restraining" thing or person. As a side note this interpretation also may suggest that the author of 2Thess was of the same mind as Paul (and may be Paul) in 1 Thess in assuming the Christ's return was imminent.