Summary: Paul writes to encourage the believers that Christ had not returned yet. They had not been left behind because if the Day of the Lord had begun, certain things would have happened already.
2 Thessalonians 2:1-5 1 Concerning the coming of our Lord Jesus Christ and our being gathered to him, we ask you, brothers, 2 not to become easily unsettled or alarmed by some prophecy, report or letter supposed to have come from us, saying that the day of the Lord has already come. 3 Don't let anyone deceive you in any way, for that day will not come until the rebellion occurs and the man of lawlessness is revealed, the man doomed to destruction. 4 He will oppose and will exalt himself over everything that is called God or is worshiped, so that he sets himself up in God's temple, proclaiming himself to be God. 5 Don't you remember that when I was with you I used to tell you these things?
Intro: Have you ever been forgotten or left somewhere by your parents or by someone else who was responsible for you in some way? I can only think of 1 time at a little mall in Ontario, OR. I can also say that I’ve both accidentally and intentionally left kids/teens behind when we were on road trips – but I always went back for them. Reminds me of the guy who said, “My family moved a lot when I was little, but I always found them.”
-Well, I don’t know if you’ve ever worried that you might be left behind when the Lord returns, but it appears that some of the Christians in Thessalonica did. See, they were being persecuted for their faith and were going through tribulation. That in itself may not have been enough to make them think they’d missed the bus, however. Apparently, someone in their group had spoken a prophecy (supposedly from God, by the Spirit of God – or sent a letter with Paul’s name on it), saying that they were living in the Day of the Lord, and that the Great Tribulation was upon them. They were no strangers to tribulation, but what caused them to become unsettled or alarmed was the fact that the wrath of God was going to be poured out on the earth. Now whether 1 Thess. was written first or not, Paul had already taught them that believers would not face the wrath of God: 1 Thessalonians 1:10 “…and to wait for his Son from heaven, whom he raised from the dead-- Jesus, who rescues us from the coming wrath.” 1 Thessalonians 5:9 “For God did not appoint us to suffer wrath but to receive salvation through our Lord Jesus Christ.” Paul had also taught them that the Lord could return at any moment. The early church believed that the Lord’s coming was near, the Judge was at the door, and that Jesus would return like a thief in the night. We call this the imminent return of Jesus because it could happen at any time.
-So, Paul writes to encourage the believers that Christ had not returned yet. They had not been left behind because if the Day of the Lord had begun, certain things would have happened already. I believe he was giving them some signs of the Day of the Lord, not so they could expect to see those signs before Jesus came back, but by the absence of those signs, they would know that Jesus had not forgotten them or abandoned them to suffer through the Great Tribulation and the Day of the Lord!