People are fascinated by what happens after death. At any given time the booksellers’ shelves have one to several best sellers about someone who claims to have died, gone to heaven (rarely hell) and returned to tell about it. Ignoring that most of these books do not agree on particulars, and the broad strokes can be accounted for by shared cultural expectations, people want to know what will happen after we die. Nor is it a new phenomenon. After all, the whole purpose of monumental burial (think the pyramids, or any cemetery) is to prepare or preserve a body for the afterlife. Strangely, with all the books about what happens after death on the shelves, few people consult the Bible on the subject. Well, perhaps not strangely, since the Bible is essentially silent about the matter, and what it does say contradicts most of the books.
Throughout the Hebrew writings there is extremely little about what happens after death. If reading the Psalms, for instance, one gets the impression that once a person is dead they go into the grave and that is the end of the matter. “I am counted with them that go down into the pit: I am as a man that hath no strength: Free among the dead, like the slain that lie in the grave, whom thou rememberest no more: and they are cut off from thy hand.” (Ps 88:4-5) And yet the Jewish people had a concept of the resurrection of the dead.
Actually, even two millennia ago that was a major point of contention for the Jews. The Sadducees denied a resurrection; the Pharisees advocated for it. Jesus argued in favor of resurrection, using the Old Testament scriptures. (Matt 22:28-33) Paul used the argument to his own advantage. (Acts 23:6-10)
The New Testament scriptures are as vague about what happens after death as the older scriptures. One, and only one, passage seems to indicate some sort of consciousness after death. That is the story of the rich man and Lazarus (Lk 16:19-31). Because this is the only passage that indicates that the dead possess any awareness, some have said this was merely a parable in order to make a point. They say Jesus used the beliefs of the day (of some people) in his teaching, whether the beliefs were valid or not.
Paul seemed to think that the dead remained in the grave until the final resurrection. This was what he taught the Christians of Thessalonika who worried about what would happen to those who had died when Christ comes.
For this we say unto you by the word of the Lord, that we which are alive and remain unto the coming of the Lord shall not prevent them which are asleep. For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God: and the dead in Christ shall rise first: Then we which are alive and remain shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord. (1 Thes 4:13-18)
Note that Paul does not say that Jesus will bring the dead with him. Instead, they will rise from the grave, and then all will simultaneously go to be with the Lord forever. Paul uses the metaphor of sleep for those who are dead and awaiting the resurrection.
Is Paul in conflict with Jesus? Not necessarily. Does it really make a difference? Definitely not. People argue over this issue, when they neither know the answer nor know why it matters. What happens to us after we die is infinitely less important that what we do in this life to prepare for what happens after we die.