CHRONOLOGICALLY, this chapter is divided into 2 sections: now & then. The 1st part deals with the present; the last section, the future. More specifically, the first 12 verses challenge us to live righteously; the last 6 give us a reason & motive to do so: the rapture. Jesus is coming soon. At least, He could come soon. And, because of the impending return of Christ (in the air to rescue & receive us), we should be living circumspectly. That is both a positive (vs. 18) & a negative motivator (vs. 6).
We should be doing the will of God (vs. 3). What is His will? Holiness, faith, spiritual growth, separation from evil, humility, love, diligence, honesty – these are the things that the Spirit of Christ is working to produce in us. It is called godliness. God wants to convert us into practical reflections of His Son. And one way or another, He will succeed (1st John 3:2). But we should be striving for the mastery here & now. We should be on board with His agenda. After all, He is the one to whom we will answer.
Now, let's really get down to the future "then" in this chapter. Verses 13-18 is quite a marvelous prophetic revelation concerning an event that is commonly called The Rapture of the church. Notice what is taught explicitly by the Apostle Paul here. The death of a Christian is only a temporary inhibition. Our sorrow is different than that which the lost souls around us endure. We have hope (a certain positive anticipation of better things). The living Christ will bring the souls of our “sleeping" loved ones with Him at the rapture. Some of us will miss death altogether. The bodies of “sleeping” Christians will be raised to life to be rejoined with their souls. The triumphant church will literally fly away to meet together for the first time as a whole, in one assembly in the sky. We will never be separated from each other (or from Christ) ever again.