In ch.1 of First Thessalonians, Paul commends the saints for believing the gospel, and maintaining a bright testimony for the Son of God, in the midst of a pagan world. In ch.2, Paul reminds the Thessalonians of his behavior among them, to show that he loved and cared deeply for them. In ch.3, Paul explains that he greatly desired to see them again, and attributed the riots of Acts 17 to Satan's efforts to hinder him. Paul says that he was "bereaved" of their company, and "separated for a little moment in person, not in heart" (1 Thess. 2:17). This was to show that his sudden departure was no indication that he loved them any less. If anything, the epistle would show that Paul had a special place in his heart for new converts. It was Paul's great love for the Thessalonians that caused him to send Timothy back to Thessalonica while Paul was in Athens (1 Thess. 3:1). When Timothy returned with a good report, it caused Paul to praise the Lord, and beseech Him for an opportunity to return to Thessalonica in person. Nevertheless, Paul recognized that he would have to wait for God's direction. By the language of ch.3, it would appear that the timing of the first epistle was shortly after Timothy's return; "Timotheus having just come to us from you" (1 Tim. 3:6). Since Paul was only a short time in Athens, he probably wrote 1 Thessalonians from Corinth, where he stayed for eighteen months.
Apparently, Timothy's report of the Thessalonians involved a number of matters. Paul addressed these in ch.4-5 of the epistle. They needed to be reminded to continue in practical holiness and love (1 Thess. 4:1-12). Being converted only a short time earlier, practical instruction was needed. Also, an eschatological issue had arisen. Paul had taught the Thessalonians when present of the coming kingdom and reign of Christ. In fact, the Jews brought this up when accusing Jason, etc. before the magistrates of harboring Paul; "these all do contrary to the decrees of Caesar, saying, that there is another king, Jesus" (Acts 17:7). The knowledge of the appearing and reign of Christ according to Old Testament prophecy was a great joy to the assembly in Thessalonica, and they were waiting for the Son from heaven. However, some among them had died, and it raised a question in their minds; would the dead in Christ miss out on the kingdom? Paul did not want them to be ignorant "concerning them that are fallen asleep" (1 Thess. 4:13). In 1 Thessalonians 4:13-18 Paul unfolded the truth of the rapture, explaining how the dead will be raised and caught up to meet the Lord in the air, in order to be with Him and return with Christ when He comes with all His saints. Paul knew this would lead to another question: would the saints then be on earth to endure the wrath which will come before the Lord appears? In 1 Thessalonians 5:1-11, Paul reminded the saints that the Day of the Lord would be a time of judgment, which will catch the ungodly by surprise, as "a thief in the night". The saints are "sons of light and sons of day" and therefore that day will NOT overtake believers as a thief. Why? "Because God has not set us for wrath, but for obtaining salvation through our Lord Jesus Christ". In the final verses, 1 Thessalonians 5:12-28, we have exhortations concerning our conduct while we wait for the Savior to come.