In Paul’s letters to the Saints in Thessalonica, he reminds the Saints that he had taught them the truth and how to live. He teaches them to remain faithful until Christ would return and that a falling away would come before the time of the Second Coming.
“The Occasional Nature, Composition, and Structure of Paul’s Letters,” Eric D. Huntsman, in How the New Testament Came to Be: The Thirty-fifth Annual Sidney B. Sperry Symposium
“Paul, Silvanus (Silas), and Timothy had come to Thessalonica early in the Second Missionary Journey, about AD 50, and had spent only a few weeks in the city where they had established a largely Gentile congregation. Dated to AD 50 or 51, Paul’s two letters to the Thessalonians are generally considered to be the earliest of his preserved writings, and the formal occasion for Paul’s writing is his concern for the further instruction of these new Saints.  Lacking Paul’s later focus on righteousness by faith rather than by the works of the law, much of these letters consist of ethical exhortations as Paul endeavors to teach these new Christians how to live as Saints (see 1 Thessalonians 4:1–12; 5:12–22; 2 Thessalonians 3:6–15).
“Nevertheless, considerable portions of both letters to the Thessalonians are devoted to treating the specific topic of the Parousia, or glorious return of Jesus Christ (see 1 Thessalonians 4:13–5:11; 2 Thessalonians 2:1–12), which included the promise that those who were Jesus’ at His coming would live with Him forever. While this part of Paul’s teaching is best preserved in 1 Thessalonians 4:13–18, this same passage also makes clear that it caused some confusion among the Thessalonians that Paul’s letter sought to resolve: because the Thessalonians, and possibly Paul himself, expected the Lord to return soon, they were concerned when the Parousia did not happen immediately and, furthermore, when members of the congregation began to die before Jesus’ return. Accordingly, Paul explained in his first letter that ‘the dead in Christ shall rise first’ to be followed by those who were alive at His coming who would be ‘caught up together with them in the clouds, to meet the Lord in the air’ (1 Thessalonians 4:16–17). This preoccupation with Jesus’ return, however, seems to have been at the heart of Paul’s second letter, where he needed to moderate the enthusiasm of the Thessalonians, noting some of the significant signs that would precede the Parousia (see 2 Thessalonians 2:1–12) and encouraging the Saints with admonitions to work that seem to have been occasioned by the ‘disorderly walk’ (ataktos peripatountos) or idle behavior of Saints whose indolence seems to have been the result of an unrealistic expectation of an imminent Second Coming (see 2 Thessalonians 3:6–15).”
“Paul as a Witness of the Work of God,” Ted L. Gibbons, in Go Ye into All the World: Messages of the New Testament Apostles, 31st Annual Sidney B. Sperry Symposium
“Paul was a witness of what a great missionary should be. In his letter to the Saints at Thessalonica, he spoke of his boldness (1 Thessalonians 2:2), the trust of God in him (1 Thessalonians 2:4), his determination to say what God wanted him to say (1 Thessalonians 2:4), his refusal to flatter to obtain success or advantage (1 Thessalonians 2:5), and his refusal to seek glory for himself or to be burdensome to his converts (1 Thessalonians 2:6). He spoke of his gentleness (1 Thessalonians 2:7), his labor and travail both night and day so that he could stand blameless before God (1 Thessalonians 2:9), his commendable behavior (1 Thessalonians 2:10), and his gratitude to God for the privilege of serving (1 Thessalonians 1:2; 2:13).”
“Apocalyptic Imagination and the New Testament,” Thomas A. Wayment, in Go Ye into All the World: Messages of the New Testament Apostles, 31st Annual Sidney B. Sperry Symposium
“In Paul’s second general epistle to the Saints of Thessalonica, it appears that some had quit their jobs, possibly in anticipation of the Second Coming. Paul reports, ‘We hear that there are some which walk among you disorderly, working not at all, but are busybodies’ (2 Thessalonians 3:11). Whatever the nature of their actions, it becomes a matter of concern for Paul, who sees their attitude as slothful and commends the members of the Church to discontinue association with them if they will not repent (2 Thessalonians 3:14). These members appear to be guilty of being slothful and apathetic in their duties as Christians.”
“1 Thessalonians and 2 Thessalonians,” New Testament Student Manual
This helpful study guide provides an outline of these two books, with historical perspectives, major themes in the books, and commentary.
“Scribes and Ancient Letters: Implications for the Pauline Epistles,” Lincoln H. Blumell, in How the New Testament Came to Be: The Thirty-fifth Annual Sidney B. Sperry Symposium
First and Second Thessalonians directly bear the name of Paul. How much of the text is genuinely Paul’s? In 2 Thessalonians 3:17, “Paul characteristically points out that he is the one actually writing the postscript, but then he follows up by somewhat enigmatically reporting that ‘this is the mark in every letter of mine; it is the way I write.’ This last statement is to be understood in light of the forged letters that were circulating, presumably in Paul’s name, that he warns the Thessalonians about earlier in the letter (2:2). But even in this context, it is still somewhat unclear exactly what Paul is saying. If Paul intended it to mean that he always added an explicit autographed postscript with a subscription to his letters in order to show their genuine authenticity, then what about the six letters that lack such an explicit postscript with a subscription? Likewise, if he is simply telling the Thessalonians that all letters written specifically to them contain an explicit postscript, then why does 1 Thessalonians not contain one? Possibly the best way to understand this remark is that Paul may have always written the concluding remarks of each letter with his own hand, but he did not always explicitly point this out.”