Using Greek resources as a guide, I constructed the following rough translation of 2 Thess. 2:6-9, mostly following the word order of the original Greek, and including various inferences of the Greek words:
Now, brethren, concerning the coming of our Lord Jesus Christ and our gathering together to Him, we ask you, 2 not to be soon shaken in mind or troubled, either by spirit or by word or by letter, as if from us, as though the day of Christ had come. 3 Let no one deceive you by any means; for that Day will not come unless the falling away comes first, and the man of sin is revealed, the son of perdition, 4 who opposes and exalts himself above all that is called God or that is worshiped, so that he sits as God in the temple of God, showing himself that he is God.
5 Do you not remember that when I was still with you I told you these things? 6 And now you know what is restraining, that he may be revealed in his own time. 7 For the mystery of lawlessness is already at work; only He who now restrains will do so until He is taken out of the way. 8 And then the lawless one will be revealed, whom the Lord will consume with the breath of His mouth and destroy with the brightness of His coming. 9 The coming of the lawless one is according to the working of Satan, with all power, signs, and lying wonders.
Biblical scholars identify the "man of sin" and the "lawless one" as the Antichrist, and identify "He who now restrains" as the Holy Spirit. Since the subject of the passage is "the coming of our Lord Jesus Christ", the "taken out of the way" of verse 7 is a reference to the "rapture" described in 1 Thess. 4:13:18. The explanation is that the Holy Spirit is in all believers, so that when the believers are taken way by Christ, the Holy Spirit thus is also taken away.
6 And now you know [perceive, understand] what holds [holds back, holds accountable] that he may be revealed in [this] his time [due season, opportunity].
7 For the mystery [as of a secret society] already works [is effective, is evident] of [that] iniquity [lawlessness], only he who holds [holds back, holds accountable] [will do so] now [henceforth] out of the way [midst, among them] is done [he is taken].
8 And then [at that time] shall be revealed that wicked [lawless] one whom the Lord Jesus will kill with the Spirit of his mouth and [alse, even] shall destroy [do away with, bring to nothing] with the brightness [appearing] of his coming [presence].
9 [Even him] who is [the one] coming after [the manner of] the working [operation] of Satan with all [manner or means of] power [miracle-working, mighty wonderful work] and signs [tokens of the supernatural, miracles] and lying [false] wonders.
The Holy Spirit was given to the apostles by Jesus (John 20:22) and first given to other believers at Pentacost (Acts 2) and ever since. The epistle of Paul to the Romans makea clear that only true believers have the Spirit, because in Romans 8:9, last part of the verse, it says "Now if anyone does not have the Spirit of Christ, he is not His." (NKJV), and in Romans 8:16 it explains "The Spirit Himself bears witness with our spirit that we are children of God." (NKJV) The fact that the Holy Spirit confirms salvation is also taught in 2 Corinthians 1:22 ".. [God] who also has sealed us and given us the Spirit in our hearts as a guarantee." (NKJV)
My observation is that since the Holy Spirit restrains (or holds back, or holds accountable) the working of lawlessness and the appearing of the lawless one, He does this restraining through the believers that He indwells. When I think about this, I envision the Christians as a bunch of people pushing back on a wall that is about to collapse, threatening to cause an entire building to collapse. At the rapture, Christ snatches them away, and the building collapses. Perhaps this is how the US will fall as a world power and cease to have a role in Tribulation prophecy.
The lesson here is that we believers should be diligent to restrain, or at least hold accountable, all forms of iniquity where we can exercise any impact. In particular, in this election season, we should be voting against any charismatic, lawless deceiver who could be the lawless ONE.