There were still dangers that beset these dear saints, habits of years that more or less characterized the heathen, if not all men. Immorality was one of them, impurity in life by habit so ingrained in them that it was hard for them to realize that it was sin. Such is the case in the Christian (so-called) world today. Evangelized Christendom is not free from this danger but rather leads the world in it.
God's commandment was sanctification to abstain from fornication. Our vessels should be possessed in sanctification and honor.
They were not to defraud one another as to fornication or adultery by taking another man's wife. God will avenge all such, and we have been called unto holiness. The body was now to be used for the Lord.
The saints in Thessalonica had set an example of love and care one for another. Now they are exhorted to abound in it, more and more. They were to walk quietly, working with their own hands so as to be no man's debtor but that the Lord might be glorified in the matter also.
How precious the truth of the Lord's taking a sinner and spiritually washing him daily until, instead of the old habits prevailing, the pressure of the new, under grace, deadens the old.
The coming of the Lord, so fresh in the sight of the saints in their spiritual mind, is spoken of in every chapter of the first letter to the Thessalonians, only in different ways. In verses 15-17 we have the immediate, blessed hope before us, immediate because we expect His coming at any moment.
After the resurrection, when the Lord in God's time returns in judgment to the earth, God will bring all of His people with Him, but the believers' immediate hope is the time of the rapture when at the shout of victory, the voice of the archangel (heavenly authority), and the trump of God (the power that raises the dead) will cause all the dead and living among believers to be raised, changed, and caught away as we "meet the Lord in the air: and so shall we ever be with the Lord." We are to comfort one another with these words. In verse 14, the "even so" means just as Christ rose and was caught away in a cloud, so shall we.