I Thessalonians was the first letter written by Paul to the young congregation he gathered in the city of Thessalonica. God gave Paul a vision whereby he understood that his party was to go and preach the gospel in Macedonia. After ministering in Philippi they traveled to Thessalonica and preached there. He stayed there possibly nearly 4 weeks, but also possibly barely over two (three sabbaths, Acts 17:2). Some of the Thessalonians believed. Those Jews who did not caused such an uproar they had to leave the infant congregation and move to the next town. After a period of time in Berea, Paul left Silas and Timothy there and went to Athens in Greece. Evidently they met him there and were sent back for a time to Macedonia before meeting him again in Corinth (cf. Acts 17:14-15; I Thess. 3:1-6; Acts 18:5). From Corinth, and possessed of good news from Timothy, the apostle writes to the Thessalonian Christians.
Paul writes to encourage the Thessalonians. This he does by his memory of and thankfulness for them. He prays for them regularly (1:2-3ff.). Good memories lift the spirits. It is encouraging to know others are praying for you. Paul affirmed them in their faith, hope and love (cf. 1:3; 3:6).
Paul writes to exhort the Thessalonians. Their walk with the Lord must not remain static, nor go backwards. They must move forward; they should abound more and more (4:1). Knowing the commandments of God, they should obey them and love one another according to the love God has taught them (4:2,9-10). Not only are they to love another, they are to deal honestly with those outside the church (4:12), even their enemies that persecute them (2:14).
Paul writes to correct their errors. This he does by demonstrating the false way and by teaching the true way. He encourages, comforts and edifies by the blessed hope of the resurrection of the Lord Jesus Christ. The dead are not gone; they are "asleep in Jesus." The Lord will return for the living and the dead, and all those in Christ will forever be with the Lord (4:13-17).
What a blessed benefit that the absent apostle encourages, exhorts and teaches this young flock through an inspired epistle. These inspired words also teach, exhort and encourage all of us "who have hope."