Okay, here is the full passage:
2 Thessalonians 2:3 Let no man deceive you by any means: for that day shall not come, except there come a falling away first, and that man of sin be revealed, the son of perdition; 4 who opposeth and exalteth 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. 5 Remember ye not, that, when I was yet with you, I told you these things? 6 And now ye know what withholdeth that he might be revealed in his time. 7 For the mystery of iniquity doth already work: only he who now letteth will let, until he be taken out of the way. 8 And then shall that Wicked be revealed, whom the Lord shall consume with the spirit of his mouth, and shall destroy with the brightness of his coming: 9 even him, whose coming is after the working of Satan with all power and signs and lying wonders, 10 and with all deceivableness of unrighteousness in them that perish; because they received not the love of the truth, that they might be saved. 11 And for this cause God shall send them strong delusion, that they should believe a lie: 12 that they all might be damned who believed not the truth, but had pleasure in unrighteousness.
The way I understand this is that God is the 'he' in verse 7 because it's when He is taken out of the way that the Wicked will be revealed. The Holy Spirit is currently preventing the final antichrist from assuming dominion.