These verses teach that those who have died before the coming again of Jesus, will have a share in that glorious event. In writing to correct the thinking of the Thessalonians, Paul has given inspired comfort to the bereaved souls of all believers.
1 Thessalonians 4:13 "But I do not want you to be ignorant, brethren, concerning those who have fallen asleep, lest you sorrow as others who have no hope."
Far from that, it is often confidence in a revealed message. The solid ground of faith is the sure Word of God, unshaken and unalterable.
The hope here that is contrasted with the hopelessness of others has to do with those believers who have "fallen asleep" physically. But death is not the end, they have entered a wonderful place of blissful, conscious existence literally.
Luke 20:38 "For He is not the God of the dead, but of the living, for all live in Him."
In Exodus 3:6 God acknowledged a continuing relationship with Abraham, Isaac and Jacob, though they had died long before. Ryrie
After Lazarus had died Jesus said of him,
Luke 16:25 "Now he is comforted."
Death for the believer means gain (Philippians 1:21 ), because there will be union with Christ without the limitations of this life. To depart and to be with Christ which is far better. (Philippians 1:23 ). Those who believe who have put off the body by death, live the "far better" life with Christ, between death and the resurrection of their bodies.
The unbelieving have no hope (1 Thessalonians 4:15 ). Theirs is hopeless grief - and they are without God. Those in Christ experience the comfort of God.
1 Thessalonians 4:14 "For if we believe that Jesus died and rose again, even so God will bring with Him those who sleep in Jesus."
What a great "even so." What God did in raising His Son, He is going to do again in raising all who physically fall asleep in Jesus. The assurance is based upon the tremendous and undeniable fact of the death and resurrection of Jesus Christ.
1 Thessalonians 4:15 "For this we say by the Word of the Lord."
This true message comes with divine authority. A "thus says the Lord" communication - the Lord says it, therefore it is so.
1 Thessalonians 4:15 "We who are a live and remain until the coming of the Lord will by no means precede those who are asleep."
This was something that concerned the Thessalonian christians. They were full of hope for Christ's coming, but they thought the highest glories would go to those who would be alive on earth when Jesus comes; while the dead would be raised later, and so would miss the best. They were sorry for the dead, and reluctant themselves to die. The teaching from the Lord through Paul ended this erroneous dilemma. The living saints will not get a head start on the dead saints at the coming of the Lord.

What misunderstanding about the return of Christ did Paul correct?