Well, things get interesting in chapter 2 — downright apocalyptic. It seems that the Thessalonians were struggling with understanding the Second Coming (no real surprise). Paul had mentioned the Second Coming in 1 Thessalonians and offers a more comprehensive explanation in 2 Thessalonians.
(2 Thess. 2:1-2 ESV) Now concerning the coming of our Lord Jesus Christ and our being gathered together to him, we ask you, brothers, 2 not to be quickly shaken in mind or alarmed, either by a spirit or a spoken word, or a letter seeming to be from us, to the effect that the day of the Lord has come.
The false teaching
Evidently, some argued that the “day of the Lord” had already occurred, presumably at Pentecost when the Spirit was poured out or when Jesus began his ministry. We don’t know much about this strange teaching.
Gordon Fee cautions the reader to be cautious as to the conclusions we draw.
Our difficulties in understanding are the result of two further matters. First, Paul himself is not sure of the source of their misinformation, and especially as to how it could have been laid at his feet in some way. Second, his response is full of reminders of matters about which he had previously informed them while among them. These two realities together account for the major part of our challenges in understanding.
To put that another way, when two parties are in conversation about something fairly well known to both of them, the eavesdropping outsider is left with a rather large amount of guesswork as to what is going on.
When this observation is applied to the present passage, what we are especially in the dark about is how much of this takes the form of reminders and how much is new information, in the sense that former information is being configured in a new way. The net result is that the reader/interpreter has an especially high information deficit at this point, and must do the best he or she can to make sense of it all, affirming what seems to be certain and showing due caution elsewhere.
Gordon D. Fee, The First and Second Letters to the Thessalonians, The New International Commentary on the New Testament, (Grand Rapids, MI: Wm. B. Eerdmans Publishing Co., 2009), 269.
Fee summarizes the evident background of the controversy Paul is addressing —
First, it seems nearly impossible not to see this as related to some kind of misunderstanding of 1 Thessalonians 5:1–11, with its repeated mention of the day of the Lord (vv. 2, 4) and subsequent play on the themes of “day” and “night.”
Second, in all probability the content of the misunderstanding has to do with someone’s teaching that the day of the Lord is already present, or, perhaps more likely in light of the emphases in chapter 1, that it had already begun in some way. This alone seems to make sense of the argument that follows, in which Paul insists that, just as he had previously taught them, particular observable events must transpire before that day comes. The Day not only will be preceded by certain events, but also the events surrounding it will simply be too visible for any of them to miss it when it does come.
Third, such erroneous teaching that the Day has in some way already come helps to explain the emphases in chapters 1 and 3. In light of what Paul had said in the earlier letter, the increase—and unjust nature—of their sufferings gives them considerable reason for anxiety, if the Day has already appeared. This also accounts for Paul’s assurance in chapter 1 both of their own (future) vindication and of the just judgment of their adversaries. But the same reality would also support the reasoning of the unruly-idle. Since the day of the Lord has already arrived, and since they apparently took a dim view of work in any case, why should they bother with work at all?
Gordon D. Fee, The First and Second Letters to the Thessalonians, The New International Commentary on the New Testament, (Grand Rapids, MI: Wm. B. Eerdmans Publishing Co., 2009), 269–270.
Paul taught that they should endure suffering and persecution confident that all will be righted at the Second Coming. If a false teacher tells them that the Second Coming has already happened (or begun), Paul’s words of comfort would have rung hollow.
And, of course, if Jesus has already come or is in the process of returning, maybe it’s time to stop working, stop helping the poor, put on white clothes, and climb to some mountain top to meet him? This would hardly be the last time believers have been fooled by this argument!