Of the twenty-seven books in the New Testament, thirteen are letters sent by Paul either to Christian communities or individual Christians throughout the Roman Empire, within a few decades of the life, death and resurrection of the Lord Jesus Christ, for their instruction and encouragement. For each of these churches he had a distinctive message, according to the circumstances under which they were living out their new faith.
This is true of his letters to the Thessalonians, which could be summarized in Paul's opening section of the letter as 'how you turned from idols to serve the living and true God; and to wait for His Son from heaven'. Taking these verses as the theme of both the Thessalonian letters gives us an understanding of the pagan society in which they lived, and from which they had been delivered; and the future hope of the Parousia, the second coming of Christ in glory to take His people to Himself and to begin the process of judgement.