Paul asks and urges them in the Lord Jesus to keep living as they were taught, in order to please God, and encourages them to do so more and more. God's will is their sanctification: that they abstain from sexual immorality, that each know how to control his own body (or wife, depending on the translation) in holiness and honor, not in the passion of lust like the Gentiles who do not know God, and that no one wrong or take advantage of his brother in this matter. The Lord is an avenger in all these things, and God called us not for impurity but for holiness, so whoever rejects this rejects God, who gives his Holy Spirit.
About brotherly love, God himself has taught them to love one another, and they already practice it toward all the brothers across Macedonia; Paul encourages them to do so more. He asks them to aspire to live quietly, to mind their own affairs and to work with their hands, so that they walk properly before outsiders and depend on no one.
He then addresses the death of believers: he does not want them to be uninformed about those who are asleep, so that they do not grieve as others do who have no hope. If we believe that Jesus died and rose again, God will also bring with him those who have fallen asleep in him. By the word of the Lord, those who are alive and remain until his coming will not precede those who have fallen asleep. The Lord himself, with a cry of command, with the voice of an archangel and with the trumpet of God, will descend from heaven; the dead in Christ will rise first, then the living will be caught up together with them in the clouds to meet the Lord in the air, and so they will always be with the Lord. Paul ends by asking them to encourage one another with these words.