v1-2: Paul begins his application from 3.10-13. We are to live godly lives; we are not to live like those who do not know God. Our obedience is to the Lord, rather than to each other;

• we instructed you how to live in order to please God;
• we ask you and urge you in the Lord Jesus;
• what instruction we gave you by the authority of the Lord Jesus.

The authority of God, and of the Lord Jesus is to be respected in our lives.

v3: Sexual purity is the will and command of God, not some 'puritanical' teaching. We recognise that the world will not help us in this, and so we must stand firm, and make the decision to avoid, or abstain, from impure things. When our lives radiate true holiness, then we are ‘walking Bibles.’

v4: The possibility of purity; we can live the right way, in sanctification and honour.

v5: In contrast is the way of unbelievers; they are driven by the passion of lust, by selfish, human, natural desires. Although there have been many changes in the world, the human heart is no different than in the first century.

v6: "Wrong (or 'defraud') his brother"; a reference to adultery in the church. Sexual sin is a sin against God (see Gen 39.9), but also dishonours the brethren. Often it is followed by deceit, gossip, lying, slander, and schism.

v7: The clear call of God is to holiness, not to impurity.

v8: The seriousness of disobedience; we are commanded to live by God's standards; to reject this is to reject God and His word. From v1-2, these things carry the authority from God. This is further evidence that Paul knew that his letters were truly the Word of God.

God is known by the giving of His Spirit. This is especially important in this context of holiness. God has equipped us by His Holy Spirit, so that we can live holy lives. Here is His expectation, that we might live out the very life of Jesus Christ, empowered by the Holy Spirit.

v9-12: Love for others, and social conduct.

v9-10: The commendation and encouragement to continue. There was already clear evidence of love for each other, and Paul urges them to continue this. The Thessalonian Christians loved all God’s people throughout Macedonia; this implies some contact between churches; they did not exist as isolated communities.

v11: We are commanded to fulfil our responsibilities, see 2 Cor 10.13-14. This involves being faithful in our working, not finding fault with the work of others, nor consistently interfering, nor being a nuisance. Paul commands personal diligence and dedication.

v12: Live a blameless life before unbelievers, see Col 4.5. We must live carefully so as not to give grounds for criticism.

v13-18: Paul addresses a key doctrinal issue, the return of the Lord Jesus, and the state of the dead; yet this is not dry doctrine, but has clear practical implications.

v13: Death had come to some; this may be a reference to the afflictions of 3.3. In such circumstances, we need to know the truth, and that truth deals with our ignorance. The truth also brings true comfort and hope. The world has sorrow without hope, but we have sorrow with hope.

v14: The first truth, that Jesus died and rose again. Jesus' return is as certain as His first coming. When Jesus returns, He will return with those who have fallen asleep in Him, that is, Christians who have died.

v15: The word of the Lord, "the Lord's own word". Paul had received this directly from the Lord Jesus, and his readers must accept this.

There is doubt concerning the future, so Paul brings the assurance of the truth.

There is error concerning salvation, death, eternity, Christ's return; so Paul brings the accuracy of truth.

When Christ returns, some Christians will remain on earth. These will not precede those who are already with the Lord.

v16: The Lord Himself, that is, the same Lord Jesus, Acts 1.11; 2.32.

Christ's first coming was announced by an angel and special signs. His return will be announced with a loud command, with the voice of the archangel, and with the trumpet call of God. The dead in Christ will be raised first, 1 Cor 15.52, their bodies reunited with soul and spirit.

v17: Those who remain will follow. We will meet the Lord in the air, in the sky. From that point, we shall always be with the Lord. Paul's wording here implies that we should always be expecting His return.

v18: These truths bring us comfort today, because we have confidence about tomorrow.

Paul effectively sidelines false teachings;

• annihilationism teaches that there is no existence beyond this life; Paul insists that the true Christian will always be with the Lord;
• universalism teaches that all people will go to Heaven; Paul teaches that those in Him, in Christ, will be with Him;
• reincarnation teaches that the dead return to the earth; Paul insists that there is just one life on earth, after which the Christian will be with the Lord.

The assurance of Christ’s return for His people is a powerful motivation for us. Jonathan Edwards; ‘Resolved. Never to do anything, which I should be afraid to do, if I expected it would not be above an hour, before I should hear the last trumpet.’