2:1 Concerning [introduces main topic of this letter; marks transition to topic covered in first letter)]  the coming of our Lord Jesus Christ and  our being gathered [Gr. episynagoge: cf. usage in Matt. 23:37; 24:31] to him [our reunion is with Him (as well as with fellow believers)], we ask you, brothers,
2:2 [note the object of what Paul asked] not to become easily [or readily; could imply church was not as doctrinally stable as Paul desired; cf. Gal. 1:6] unsettled [shaken] or alarmed [frightened; disturbed; anxious] by [note three sources of the false report; winds of false teaching were blowing across the Thessalonian landscape; cf. Eph. 4:14] some prophecy, report [a teaching circulated in oral form; perhaps a sermon] or letter [perhaps a document falsely attributed to Paul and companions] supposed [perhaps suggests letter forged Paul’s signature] to have come from us, saying that the day of the Lord [cf. 2 Thess. 1:5-10] has already come.
Note: What rumor caused confusion among the Thessalonian believers? Is it easy or difficult to maintain confidence in the truth when confronted with rumors? What rumors have you heard in recent years pertaining to Christ’s return? How could you use this lesson passage to help people who hear or spread rumors about Christ’s return?
2:3 Don’t let anyone deceive you in any [deception can come in many forms and through many avenues] way, for that day will not come until  the rebellion [Gr. apostasia: can mean “departure;” abandoning God; revolt against God; deserting one’s faith in God (suggests that professed (as opposed to true) Christians will abandon their profession of faith in Christ] occurs and  the man of lawlessness [Satan’s supreme representative and tool; cf. 2:9; the Antichrist (cf. Rev. 8); the leader of the great eschatological rebellion against God] is revealed, the man doomed to destruction.
Note: An end-time rebellion or “falling away” is mentioned in the following verses:
• 1 Timothy 4:1-2
• 2 Timothy 4:3-1
• 2 Peter 2:1-3; 3:3-4
• Jude 17-18
2:4 He will oppose [literally, “he who opposes” or “the adversary”] and will exalt himself over [cf. use of “above” in Isa. 14:12-14] everything that is called God or is worshiped, so that he sets himself up in God’s temple [not necessarily temple in Jerusalem; in the sense that he takes and claims God’s place of residence and rule to be his own], proclaiming himself to be God.
2:5 Don’t you remember [indicates they had forgotten Paul’s teaching or that they were confused by what the false teachers were saying (cf. 2:2-3)] that when I was with you I used to tell you [denotes repeated times of instruction] these things [Paul had taught the Thessalonians about the second coming of Christ and the end times]?
2:6 And now you know what [possible “restrainers” include the government (laws that help curb evil); the ministry of the church; the Holy Spirit] is holding [restraining] him back, so that he may be revealed at the proper time [in God’s time].
2:7 For the secret [mystery; something hidden, but something God will reveal] power of lawlessness [the force from which all sin springs] is already at work [cf. 1 Jn. 2:18]; but the one [restrainer] who now holds it [lawlessness] back [restrains] will continue to do so till he is taken out of the way [at which time the man of lawlessness will act as indicated in 2:2-4; at that time lawlessness will operate unchecked].
2:8 And then [after the restrainer has been removed] the lawless one will be revealed, whom the Lord Jesus will overthrow [“consume” (KJV)] with the breath [indicates the awesome power of God who will blow out the flame of the man of lawlessness with a single breath] of his mouth [that is, by His word (cf. Isa. 11:4)] and destroy [“nullify” or “render ineffective or powerless;” there will be an end to the evil done by the man of lawlessness] by the splendor of his coming.
2:9 The coming of the lawless one will be in accordance with the work of Satan displayed in all kinds of counterfeit [“of falsehood;” indicates that not all miracles are from God] miracles [displays of power], signs [significance of displays of power] and wonders [impact of displays of power on those who witness but cannot explain them; cf. Matt. 24:24],
2:10 and in every sort of evil that deceives [the goal of “every sort of evil;” cf. Rev. 13:13-14; 16:14;19:20] those who are perishing. They perish because [for this reason] they refused [indicates they still had opportunity to respond to God’s offer of salvation; to reject] to love the truth [in particular, the gospel message] and so be saved [outcome of wholeheartedly embracing the truth].
Note: How can you recognize false prophets?
2:11 For this reason God sends [indicates sovereignty of God; God is always in control, even when it appears that evil is gaining the day] them a powerful delusion [literally, “a working (or, energizing) of error”] so that they will believe the lie [the claim of the man of lawlessness to be God (2:4)]
2:12 and so that [result of choosing to “believe the lie”] all will be condemned [result of choosing to “believe the lie” (2:11)] who have not believed the truth but have delighted [welcomed and embraced wickedness (cf. Jn. 3:19)] in wickedness.
2:13 [Paul followed up his words about the fate of unbelievers with encouragement to the Thessalonian believers to stand firm] But we ought [Paul felt an obligation to thank God for the Thessalonians] always to thank God for you, brothers loved [a continuing and undiminished love] by the Lord [we must never forget (especially in times of persecution and difficulties) that the Lord loves us], because from the beginning [refers to eternity past; cf. Eph. 1:4] God chose [salvation begins and ends with God; cf. 1 Thess. 1:4-5] you to be saved through the sanctifying [sanctification is the gradual, lifelong process of being conformed into the image of Christ that will be completed when believers see Christ face-to-face (cf. 1 Jn. 3:2)] work of the Spirit and through belief [acceptance] in the truth [the gospel message of salvation through Christ].
2:14 He called you to this [refers to salvation through the Spirit’s work and to Christians believing the gospel] through our [God worked through Paul and his companions who carried the gospel to Thessalonica] gospel [the means God used to make known His call to sinners for their salvation], that you might share in the glory of our Lord Jesus Christ.
2:15 So then, brothers [the whole Christian community], stand firm and hold [keep a firm grip, especially when persecution intensifies] to the teachings [sound doctrine is the best antidote to false doctrine] we [as opposed to the false teachers mentioned in 2:2] passed on to you, whether by word of mouth [Paul’s oral instruction when present] or by letter [Paul’s written instruction when absent].
Note: What hinders Christians from standing firm?
2:16 May our Lord Jesus Christ himself and God our Father, who [Father and Son] loved [demonstrated on the cross] us [Paul included himself] and by his grace gave us [Paul included himself] eternal [reached into eternity] encouragement and good [in content and duration] hope,
2:17 encourage [comfort] your hearts [entire inner life] and strengthen [undergird and support] you in every good deed [actions] and word [speech].