In Chapter 2 of Thessalonians, Paul speaks of the parousia. The day of Christ's return is not yet because the great rebellion has not yet occurred and the "man of lawlessness" has not yet been revealed.
 v1. Paul describes the last day as a "coming" of Jesus and a gathering together of believers, Matt.24:31.
v2. Concerning the second coming, Paul does not want his readers led astray by false teachings which claim that the "day of the Lord has already come", cf. 1Thess.5:2.
v3. Paul makes the point that "the day" hasn't already come because certain preliminary events have not yet occurred. There must first be the "rebellion". This is a time of great apostasy, a rebellion of both church and state against God. Then the "man of lawlessness" must be revealed. This "man", Mr. Loss, is most likely the antichrist. He is the one who is doomed to destruction, but first he must be revealed.
v4. The antichrist is the one who "opposes" God, exalts himself over God and claims deity for himself.
v5. Paul had already told his readers all this when he was with them. If only we knew what he had actually told them!
v6-7. At the present moment, the antichrist rules quietly, awaiting the day of his revealing. The reference to "the restrainer", the one holding him back, is a misreading of the Greek.
v8. In the final day the antichrist will be revealed in all his horror, and once he displays his real self he will be destroyed by Christ. His revealing is imaged in the revealing of the beast who, in coming out of the primeval bog, displays the pure horror of his person, Dan.7, Rev.13. Jesus, at his second coming, will destroy him with a word.
v9. Jesus will come with splendor, but the antichrist also has a "coming" (the same word is used for Jesus' coming) and it too will be in splendor. The display of his glorious power is described in the same terms used of Jesus' demonstrations of power. The antichrist comes as Satan's representative, cf. Rev.13.
v10-12. The coming of the antichrist will deceive many. Many will follow him, and it is most likely that the deceived ones will include church members, cf. Matt.24:24. They are deceived because they do not possess the truth of the gospel; false teaching has undermined their salvation. God then acts in judgement to accentuate their rebellion by deluding them. The result of the delusion is that those who follow the antichrist will receive the judgement due them.
 When Paul writes his second letter to the church at Thessalonica, he is writing to a church totally focused on the second coming of Christ. Some of the members had even given up their jobs and were sitting around waiting for the day of Christ's return. So, Paul lets them into a secret. Before Jesus comes there will be the rebellion and the coming of the man of lawlessness. This evil man, the man of sin, Mr. Loss, is even now causing trouble. Yet, it's only when he fully breaks loose that the end is upon us. In Paul's day, as in our day, Mr. Loss is around causing us some pain, but he is not in full-blown destruction mode, he is not revealed ("coming") in all his glory.
Mr. Loss, revealed elsewhere in the scriptures as the antichrist, is rather difficult to identify because he takes on many shapes. He can be a political leader, a philosophy, a heresy, a revolutionary group...... yes the day may even come when he is a rouge computer.
Paul says that "the secret power of lawlessness is already at work", although yet to be "revealed." So, what is he up to right now, what is he doing?
First, he opposes and exalts himself over everything that is God's. He intrudes his evil into the fellowship of believers and claims of himself the status of God, v4. This is why he is often a heresy articulated by fanatics.
Second, he is running the secular agenda. Verses 6 and 7 seem to suggest that there is something or someone restraining his present activities, but this is most likely a translation problem. The word "restrain" can actually be translated "rule". So, it is more likely that Paul is saying that the antichrist is actually running things for the present. Remember, Satan has "the whole world in his hand" cf. Luke.4:5-8. None-the-less, the day is coming when he will break out in total evil.
Third, he deludes humanity, including believers, v9-12. His "coming", or manifestation, is similar to Christ's coming. He comes with "miracles, signs and wonders", but they are "counterfeit" and "evil". His focus is on those who are not confident in their salvation. At first reading, those who have "refused to love the truth and so be saved" may seem like godless pagans, but the description most likely includes "apostate" believers. Their salvation is undermined because they do not rest on gospel truth; they have "not believed the truth." Their delusion prepares them for the judgement of God in the day when Mr. Loss finally displays himself.
So there he is, Mr. Loss. There is only one place of safety in the presence of the antichrist and this is at the foot of the cross.
 1. Discuss the "rebellion" in the terms of a falling away of believers.
2. Discuss the possibility that Mr. Loss is a false doctrine intruding itself into the church and thus undermining our salvation.
3. Examine the ruling role of Mr. Loss. Discuss the line from the children's chorus "He's got the whole world in his hand" in light of your observations.