Who or what is the restrainer?
2 Thessalonians 2:3-8 "...Let not any one deceive you in any manner, because [it will not be] unless the apostasy have first come, and the man of sin have been revealed, the son of perdition; who opposes and exalts himself on high against all called God, or object of veneration; so that he himself sits down in the temple of God, shewing himself that he is God. Do ye not remember that, being yet with you, I said these things to you? And now ye know that which restrains, that he should be revealed in his own time. For the mystery of lawlessness already works; only [there is] he who restrains now until he be gone, and then the lawless one shall be revealed, whom the Lord Jesus shall consume with the breath of his mouth, and shall annul by the appearing of his coming..."
There are really only two viable options for identifying the restrainer. 1. Michael the archangel, and 2. The Holy Spirit.
The restrainer is holding back the full manifestation of sin, which ultimately is the lawless one, the man of sin. Paul in writing to the Thessalonians does not directly identify the restrainer, but if we consider what is being held back and what keeps the man of sin from being manifested in the fullness Satan desires, we can identify Him as the Holy Spirit.
First, the option of Michael as restrainer, is intriguing and has much to commend it, but falls in an important and key area. Namely verse 7. The mystery of lawlessness "works" throughout the church age, as evidenced by being "already at work" when Paul wrote this epistle. This tells us that the restrainer must have a measure (worldwide) of omnipresence. The power is also immense and only the Holy Spirit is a person with sufficient power. We suggest that the Holy Spirit restrains the evil of this age, and its ultimate outcome and manifestation/goal (the man of sin) in two ways:
1. Primarily: The indwelling Spirit, in Christians, whose presence in salt and light hinders the swelling tide of evil and lawlessness.
2. Secondary: It is quite likely that the Spirit also hinders through human government and divine providence, in the affairs of men to restrain what Satan desires. God is in control, despite Satan being called the "god of this age," we must remember it is a little "g" not a big "G.".
Prior to the 7 year tribulation, the rapture takes place, and the Spirit is removed from the earth (removed in His current capacity-not removed from working in Divine purposes in the universe). He will not be at work in the present way of restraint in the tribulation period and therefore sin & lawlessness go unchecked. The lawless one, the man of sin, is then revealed, but again, this is after the "departure" which may be a twofold reference to the apostasy of professing christendom, but moreso the rapture. The former is the degradation of profession with Christianity losing its salt & light influence, and the latter being the full removal of that which is true (the church) and remained faithful until the rapture.
With Christians gone, and the indwelling Spirit removed, the restraint is gone, and the mystery of lawlessness...which is at work even now...finds its culmination in the man of sin. Daniels 70th week comes to pass, the final 7 year period characterized by judgments, Israel's time of trouble, ending in the great judgments upon the Gentile world power (see Daniel 2) and the antichrist, as well as the conclusion of this age merging into the 1000 year reign of Christ...the kingdom.
For followup: http://www.middletownbiblechurch.org/dispensa/dispch11.htm
And also; http://www.middletownbiblechurch.org/prophecy/prophe9.htm