Paul had been with the Thessalonians for only a brief time—less than one month—before he was forced to leave the city because of an intense persecution that had arisen from among the Jews (1 Thess 2:13-17; Acts 17:1-9). After Paul learned that the Thessalonians themselves had endured these trials, he wrote to the church, saying, “How can we thank God for you in return for all the joy we experience because of you before our God, as we pray earnestly night and day to see you face to face and to complete what is lacking in your faith?” (1 Thess 3:9-10). Paul wanted the Thessalonians to live pure lives as they waited on Christ’s return and Paul saw in the Old Testament ideas he could use in his argument.
(1) In 1 Thess 4:3-6, Paul echoed the Ten Commandments in exhorting the Thessalonians to express their knowledge of God by avoiding immorality. God revealed Himself to Israel at Mount Sinai (Exodus 19) and began the Ten Commandments by stating that Israel was to have no other gods before Him (Exod 20:3; Deut 5:7). In Exod 20:14 and Deut 5:18, Moses commanded Israel that they must not commit adultery. In the narrative of the Old Testament, Israel’s idolatry often resulted in sexual immorality. When Israel worshipped the golden calf Aaron made, “the people sat down to eat and drink, then got up to revel” (Exod 32:6). When Israel worshipped the gods of the Moabites, they fornicated with Moabite women (Num 25:1-6). Paul told the Thessalonians that—because they knew God—they should avoid immorality. In this way, the Thessalonians would distinguish themselves from the Gentiles who revealed by their immorality and thievery that they did not know God.
(2) In 1 Thess 4:16-5:11, Paul described the time of Christ’s return in language the Old Testament prophets employed to predict the Day of the Lord. For a span of three Sabbaths (Acts 17:1-4), Paul gathered with the Thessalonians and taught them from the Old Testament. He may have instructed them concerning the prophets’ announcements of the Day of the Lord (Isa 2:5-22, 4:2-6, 13:6-9, 66:1-24; Joel 1:15-2:11, 3:1-2; Amos 5:18-27; Zeph 1:2-18; Zech 2:10-13, 14:1-21; Mal 3:2, 4:5). In their own contexts, the prophets proclaimed a day was coming when the Lord would save His people and condemn any who opposed Him. Paul wrote that Christ’s return would mark the Day of the Lord, when God would deliver believers like those in Thessalonica and destroy with His wrath those who walked in rebellion and darkness. Paul’s instructions that the Thessalonians should pursue sanctification (1 Thess 4:1-8), love one another (1 Thess 4:9-11), and live soberly (1 Thess 5:5-8) were not simple moral exhortations. For Paul, moral integrity manifested hope that one would be identified with Christ at His return.