that you should be holy: This phrase renders a Greek expression that could also be translated “your sanctification.” Paul uses the Greek word ha·gi·a·smosʹ twice more in this context, at 1Th 4:4 and 4:7, where it is rendered “holiness.” In the Christian Greek Scriptures, the words rendered “holy” and “holiness” denote being set aside for God’s service. These terms also include the idea of purity in moral conduct. (Mr 6:20; 2Co 7:1; 1Pe 1:15, 16) In this context, holiness refers to avoiding sexual immorality, that is, certain sexual activities forbidden by God.​—See Glossary, “Holy; Holiness.”

sexual immorality: See study note on Ac 15:20.

body: Lit., “vessel.” Paul compares a person’s body to a vessel. For a person to “control his own body in holiness,” he must bring his thoughts and desires into harmony with God’s holy moral laws. The Greek term for “vessel” is used in a figurative sense also at Ac 9:15; Ro 9:22; and 2Co 4:7.

uncontrolled sexual passion: This expression renders a Greek word (paʹthos) that refers to a strong desire, or an uncontrolled passion. The same Greek word appears at Ro 1:26 and Col 3:5. In this letter to the Thessalonians, Paul combines the same word with a term (e·pi·thy·miʹa) that literally means “desire.” In this context, it denotes a covetous desire or an inordinate craving, or lust, and is therefore rendered greedy. The context makes it clear that this combined expression refers to wrong desires of a sexual nature. While sexual desires can be properly satisfied within an honorable marriage (1Co 7:3, 5; Heb 13:4), Paul shows that “Jehovah exacts punishment” for improper sexual conduct (1Th 4:3-6).

take advantage of his brother in this matter: The Greek expression rendered “take advantage of” is related to a term for “greed” and denotes a greedy, selfish view of sexual pleasure. The Greek word may also mean to “rob,” “defraud,” or “cheat.” Here it may suggest that a Christian who selfishly commits sexual sins robs a fellow Christian of a clean conscience. If either is married, the innocent mate is deprived of marital security and happiness. Such actions could also rob the individuals involved, their families, and the congregation of a clean reputation. Above all, those who commit sexual immorality show disregard for God.​—1Th 4:8.

because Jehovah exacts punishment for all these things: This phrase could also be rendered “because Jehovah is the Avenger concerning all these things.” Paul is apparently alluding to Ps 94:1, where Jehovah is addressed as “O God of vengeance.” While appointed elders are responsible for removing unrepentant wrongdoers from the Christian congregation (1Co 5:1, 13), Jehovah is the one who ultimately punishes those who sin unrepentantly by practicing sexual immorality.​—For the use of the divine name in this verse, see App. C3 introduction; 1Th 4:6.

uncleanness: See study note on Eph 4:19.

brotherly love: See study note on Ro 12:10.

taught by God: This phrase renders the Greek expression the·o·diʹda·ktos, which occurs only here in the Christian Greek Scriptures. It is composed of the Greek word for “God” and the word for “taught.” Paul may be alluding to Isa 54:13, where the Hebrew text reads: “Your sons will be taught by Jehovah.” As recorded at Joh 6:45, Jesus quotes Isaiah’s words. Other scriptures also speak of Jehovah God as one who teaches his people. (De 6:1; Isa 48:17) At least one translation of the Christian Greek Scriptures into Hebrew uses the divine name here; some translations into other languages do so as well.

taught by God to love one another: God created man in his image with the ability to love. (Ge 1:27) By his own example, God teaches humans to love. (Mt 5:44, 45; Ac 14:17; 1Jo 4:9-11) His Word repeatedly highlights the importance of showing love. (Le 19:34; De 10:18, 19; 1Jo 3:16; 4:21) According to Jesus, one of the two principal commandments of God’s Law to Israel stated: “You must love your neighbor as yourself.” (Mt 22:39; Le 19:18) The disciple James called this command “the royal law.” (Jas 2:8) Jesus added to this command by stating that Christians must love one another just as he had loved his disciples.​—Joh 13:34.

those who are sleeping in death: Lit., “the ones sleeping.” The Scriptures use the expressions “sleep” and “fall asleep” to refer both to physical sleep (Mt 28:13; Lu 22:45; Joh 11:12; Ac 12:6) and to the sleep of death (Joh 11:11; Ac 7:60; 13:36; 1Co 7:39; 15:6, 51; 2Pe 3:4). When these expressions appear in contexts that refer to death, Bible translators often use such wording as “sleeping in death” or simply “died.” The Bible’s use of this expression is fitting for at least two reasons. First, because the Scriptures show that the unconscious condition of the dead is like sleep. (Ec 9:5, 10; Joh 11:11, 13) Second, because the Scriptures give the hope that those “sleeping in death” will “wake up” to life by means of a resurrection.​—Da 12:2; see study notes on Joh 11:11; Ac 7:60.

by Jehovah’s word: In a broad sense, this expression refers to a message from Jehovah.​—Compare study notes on Ac 8:25; 1Th 1:8; for the use of the divine name in this verse, see App. C3 introduction; 1Th 4:15.

the presence of the Lord: That is, the presence of the Lord Jesus Christ. (1Th 2:19; 3:13; 5:23) One ancient Greek manuscript reads “the presence of Jesus.”

the Lord: That is, Jesus Christ.

will descend from heaven: The Lord Jesus will descend in a figurative way by turning his attention to the earth and extending his power to it. In the Hebrew Scriptures, such terms as “go down” and “stoops down” are used in a similar way. (Ge 11:5; 18:21; Ps 113:6) For example, Ge 11:5 says that “Jehovah went down to see the city” of Babel. He did so to survey the situation in Babel and determine what action to take.

a commanding call: Or “a shout of command.” The Greek word used here occurs only once in the Christian Greek Scriptures. It could refer to an order given to an army to attack or to a command issued by a king. The Lord Jesus figuratively descends from heaven to make this commanding call to awaken from the sleep of death those who are dead in union with Christ, that is, his spirit-anointed followers. The Scriptures show elsewhere that it is Jesus’ “voice” that the dead will hear (Joh 5:25) and that “in the Christ all will be made alive” (1Co 15:22).​—See study note on 1Co 15:55.

with an archangel’s voice: The Greek term for “archangel” (ar·khagʹge·los) appears only twice in the Christian Greek Scriptures and always in the singular. The Greek prefix rendered “arch” means “chief” or “principal”; therefore, “archangel” means “chief angel,” or “principal angel.” The second occurrence of “archangel,” at Jude 9, associates the term with the name Michael. Hence, in the Scriptures, Michael is the only one called “the archangel.” He is the one whom God has designated chief, or head, of the angelic hosts. At 1Th 4:16, the Lord Jesus is said to have the “voice” of an archangel and the power to resurrect the dead. (See study note on Joh 11:25.) So the expression “an archangel’s voice” apparently focuses attention on the authoritativeness of Jesus’ voice of command.​—Joh 5:26-29.

with God’s trumpet: Trumpets had various uses in the Scriptures. (See Glossary, “Trumpet.”) Here the purpose of the sounding of “God’s trumpet” is to assemble Jehovah’s people, as was done when the two silver trumpets were sounded in Moses’ day to assemble the 12 tribes of Israel. (Nu 10:1-10) At 1Co 15:52, the apostle Paul connects such a rousing assembly “trumpet” with the resurrection of spirit-anointed Christians.

be caught away in clouds to meet the Lord in the air: In this context, both “clouds” and “air” are used in a figurative sense. “Clouds” often denote invisibility.​—See study notes on Mt 24:30; Ac 1:11.

meet the Lord: That is, the Lord Jesus Christ, as shown by the context.​—1Th 4:15, 16.

be with the Lord: That is, the Lord Jesus Christ.​—1Th 4:15, 16.