Regarding 2 Thessalonians as a pseudepigraphical epistle, Early Christian Writings
quotes Norman Perrin as follows:
Norman Perrin writes the following (The New Testament: An Introduction, pp. 119-120): .... In 1 Thessalonians the parousia, the coming of Jesus from heaven as apocalyptic judge and redeemer, is imminent. When Paul speaks of "we who are alive, who are left until the coming of the Lord" (1 Thes 4:15), he clearly expects the event in his own lifetime. But 2 Thes 2:3-12 sets out an elaborate program of what must first happen before that event can occur. ....
I do not wish to dispute 2 Thessalonians as pseudepigraphical; that is my current position. But I do not think that the program of events which is laid out in chapter 2 necessarily conflicts with an expectation that such events will happen within the lifetime(s) of the author...:
1 Thessalonians 4.13-18: 13 But we do not want you to be uninformed, brethren, about those who are asleep, that you may not grieve, as do the rest who have no hope. 14 For if we believe that Jesus died and rose again, even so God will bring with Him those who have fallen asleep in Jesus. 15 For this we say to you by the word of the Lord, that we who are alive and remain until the advent of the Lord, shall not precede those who have fallen asleep. 16 For the Lord Himself will descend from heaven with a shout, with the voice of the archangel, and with the trumpet of God; and the dead in Christ shall rise first. 17 Then we who are alive and remain shall be caught up together with them in the clouds to meet the Lord in the air, and thus we shall always be with the Lord. 18 Therefore comfort one another with these words.
1 Corinthians 15.51-52: 51 Behold, I tell you a mystery; we shall not all sleep, but we shall all be changed, 52 in a moment, in the twinkling of an eye, at the last trumpet; for the trumpet will sound, and the dead will be raised imperishable, and we shall be changed.
...and/or of his readers:
2 Corinthians 4.12-14: 12 So death works in us, but life in you. 13 But having the same spirit of faith, according to what is written, "I believed, therefore I spoke," we also believe, therefore also we speak; 14 knowing that He who raised the Lord Jesus will raise us also with Jesus and will present us with you.
1 Thessalonians 5.23: 23 Now may the God of peace Himself sanctify you entirely; and may your spirit and soul and body be preserved complete, without blame, at the advent of our Lord Jesus Christ.
Indeed, the same combination of motifs — a program of events followed by the end, which is to happen within the lifetime of a person now living — occurs in Mark 13; verses 5-23 lay out a timetable of events which must happen before the end, but the end in verses 24-27 is expected before "this generation" dies out, according to verses 28-31.
2 Peter 3.3-16 offers a great example of postponing the consummation ("one day is as a thousand years, and a thousand years as one day"); 2 Thessalonians 2, however, does not claim that the day of the Lord is not
soon; it claims that the day of the Lord has not
already come:
2 Thessalonians 2.1-2: 1 Now we request you, brethren, with regard to the coming of our Lord Jesus Christ, and our gathering together to Him, 2 that you may not be quickly shaken from your composure or be disturbed either by a spirit or a message or a letter as if from us, to the effect that the day of the Lord has come [ἐνέστηκεν].
The verb in question, in the perfect tense, can mean "has come" or "is present," as we can see from other such usages:
1 Esdras 9.6: 6 And all the multitude sat in the open square before the temple, shivering because of the bad weather that prevailed [ἐνεστῶτα, perfect].
1 Maccabees 12.44: 44 Then he said to Jonathan, "Why have you wearied all these people when we are not at war [πολέμου μὴ ἐνεστηκότος, perfect]?"
2 Maccabees 3.17: 17 For terror and bodily trembling had come over the man, which plainly showed to those who looked at him the pain lodged [ἐνεστὸς, perfect] in his heart.
Romans 8.38-39: 38 For I am convinced that neither death, nor life, nor angels, nor principalities, nor things present [ἐνεστῶτα, perfect], nor things to come, nor powers, 39 nor height, nor depth, nor any other created thing, shall be able to separate us from the love of God, which is in Christ Jesus our Lord.
1 Corinthians 3.22-23: 22 ...whether Paul or Apollos or Cephas or the world or life or death or things present [ἐνεστῶτα, perfect] or things to come; all things belong to you, 23 and you belong to Christ; and Christ belongs to God.
1 Corinthians 7.26: 26 I think then that this is good in view of the present [ἐνεστῶσαν, perfect] distress, that it is good for a man to remain as he is.
Galatians 1.4-5: 4 ...who gave Himself for our sins, that He might deliver us out of this present [ἐνεστῶτος, perfect] evil age, according to the will of our God and Father, 5 to whom be the glory forevermore. Amen.
How does one disabuse a person of the notion that an event has already come and thus is present? One way is to point out that the proper signs of that event have not yet happened. (What it could mean that the Thessalonians allegedly thought that the day had come is, of course, a very interesting question in its own right, but regardless: that seems to be the idea being countered here.)
If 2 Thessalonians had been written in order to postpone the end, then I wonder why the following passages made it in:
2 Thessalonians 1.6-8: 6 For after all it is only just in the sight of God to repay with affliction those who afflict you, 7 and to give relief to you who are afflicted and to us as well at the revelation of the Lord Jesus from heaven with His mighty angels in flaming fire, 8 dealing out retribution to those who do not know God and to those who do not obey the gospel of our Lord Jesus.
2 Thessalonians 2.7: 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.
Particularly in the case of that first passage, for Jesus to give relief at his advent to "you who are afflicted" seems to assume that at least some of the readers will still be alive at that time, just as seems to be assumed in some of those other Pauline passages listed above. At least, I am not sure how I would discriminate between the Pauline passages listed above and these (pseudo-)Pauline passages in 2 Thessalonians. The advent of the Lord does not seem to have to postdate the advent of the man of sin by any great margin.
At any rate, the mere imposition of a schedule of some kind does not in any way, on its own, necessarily compromise the imminence of the end. A classic example of this, and one that eschatological writers themselves sometimes use (as in Mark 13.8), is childbirth. There are plenty of milestones along the way in the case of a healthy birth, but the mere existence of those milestones does not imply that the birth is not going to happen within a certain time frame.
Or so it seems to me.