Received my contract for this series as a book in the mail today! Previous posts include:
1a. Born at a Time and Place 1; 1b. Born at a Time and Place 2
2a. A Change in Life Direction; 2b A Change in Life Direction 2; 2c A Change in Life Direction 3
3a. The Unknown Years 1; 3b. The Unknown Years 2; 3c. The Unknown Years 3
They will of course be edited and filtered before publication.
The first post in the current chapter was Life Beyond Death 1. We now continue this chapter in progress...
So it would seem to be either at Athens or, perhaps more likely, at Corinth that Paul penned 1 Thessalonians. We would agree with perhaps the majority of scholars in thinking that 1 Thessalonians was not only the first letter of Paul's that we have, but indeed the very first book of the New Testament to be written. This chapter focuses on 1 Thessalonians, one of whose main topics is the fate of those who die before Christ returns. Then we follow that theme through some of Paul's other letters too.
In the first three chapters of 1 Thessalonians, Paul largely recounts the story of his relationship with the Thessalonians. It is helpful to remember that only part of our conversations are about ideas and "logical" statements. In fact, probably more of our communication functions on a relational and emotional level than on a logical one. Teachers of ancient rhetoric fully took these other dimensions of persuasion into account.  Logical argument they called the logos mode of persuasion. Arguments that played on the emotions of the audience played on pathos. A final mode of persuasion build on ethos, persuasion based on trust toward the person doing the persuading.
The first three chapters of 1 Thessalonians are largely about establishing ethos between Paul and the Thessalonians. Paul builds on the common experiences he and the Thessalonians have shared, as well as the good will Timothy's recent visit to them has secured. He reassures them of his good motives and the broader struggle with God against evil that they have joined.
The form of 1 Thessalonians at its core is much like normal letters of the day.  The main difference is how long the letter is (longer than most letters) and the fact that Paul expands the typical greeting. Most letters began with a simple greeting, also called a prescript: x to y, greetings. 1 Thessalonians, perhaps because it is Paul's earliest letter, expands the greeting the least of any of Paul's writings, adding a little to the nature of the Thessalonian church and providing the characteristic Pauline "Grace and peace to you" instead of the normal "Greetings." The word for "grace" (charis) was a little like the word for "greetings" (chairein), to which Paul added the characteristic Jewish "peace" (cf. shalom).
Letters then usually had a "thanksgiving" or blessing section of some kind after the greeting. The letter writer might invoke the favor of the gods on the audience. 1 Thessalonians is no different. In 1:2-10, Paul thanks God for the Thessalonians and anticipates one of the key topics he will address later in the letter--Christ's coming back to earth (1:10). All of Paul's letters have something similar right after the greeting, that is, with the exception of Galatians, where Paul perhaps shames the audience by refraining from the usual thanksgiving. 1 Thessalonians also has some very brief closing remarks (5:12-24) and a "postscript" (5:25-28).
Although 1 Thessalonians does address some other issues, the topic that seems to be its most central has to do with the question of what happens to Christians who die before Christ returns (4:13-5:11). Before he gets to the big issue, Paul does urge the Thessalonians to avoid sexual immorality (4:3-8). He urges brotherly love (4:9-10) and for the Thessalonians to work diligently. Some have suggested that the Thessalonians were so focused on Christ coming back soon that they had stopped going about the business of their daily lives. It is a fun suggestion, although in the end we do not really have enough evidence to know for sure.
It can be hard at first to get into the heads of the Thessalonians. How could they not know what happened to Christians who died before Christ came back? Paul was not in Thessalonica long before he had to leave, to be sure. But would their eternal destiny not have come up even in his first meeting with them? These sorts of things are such obvious assumptions to us that it is hard to put ourselves in the shoes of someone for whom these were radically new ideas.
However, it may also be that some of our own assumptions are unexamined. For example, do we understand the difference between the idea of resurrection that Paul presents here and the idea of the immortality of the soul, which Paul does not discuss here. Resurrection here is not something that happens at death. For 1 Thessalonians, the only one who has ever been resurrected up to this point in history is Jesus Christ himself. For 1 Thessalonians, resurrection is an event that will take place as Jesus Christ returns to earth from heaven.
Resurrection for Paul also involves a body. This aspect of resurrection is particularly clear in 1 Corinthians 15, where Paul addresses similar issues with the Corinthians. "But someone will ask, 'How are the dead raised? With what kind of body will they come?" (1 Cor. 15:35). Embodiment is so central to the idea of resurrection for Paul that the possibility that some sort of body might not be involved does not even occur to him.
For Paul, this body is not like our current bodies: "flesh and blood cannot inherit the kingdom of God" (15:50). Our body that dies is a natural body or perhaps better, an animal body (psychikos; 15:44). Our body that rises is, like Christ's, a "spiritual" body (pneumatikos). It is a body, so it is not just our spirit. It is a body with a glory, perhaps not unlike the glory of heavenly bodies like the stars, at least as they appear to us looking up from the earth (15:40-41). Obviously Paul was using the categories he had at his disposal to try to describe our heavenly bodies.
These bodies, perhaps surprisingly to some of us, will be just like Christ's resurrection body. "[J]ust as we have borne the likeness of the earthly man, so shall we bear the likeness of the heavenly man" (1 Cor. 15:49). In Philippians, Paul also says that Christ "will transform our lowly bodies so that they will be like his glorious body" (Phil. 3:21).
But how could these things not have come up while Paul was there? Is it just that Paul thought they needed reminding? On the one hand, his audience does seem overwhelmingly Gentile. It is hard to imagine that a group of Jews would have turned to God "from idols" (1 Thess. 1:9). Accordingly, they might not have known much of anything about the distinctively Jewish notion of resurrection. Most non-Jews did not really have much anticipation of a meaningful afterlife at the time.
In the end, we can probably explain what is going on here if Paul's focus in preaching was on Christ's return to earth in judgment rather than on life after death. We tend to think we will die, even though Christ will return to earth one day. The order was probably reversed exactly in Paul's earliest preaching. Christ is coming back to earth very soon, and--oh, yes--if you die before it happens there is life after death...
 The best starting resource here, and one that deserves to be on our list of top fifty books to master Paul's writings, is George Kennedy's classic book, New Testament Interpretation through Rhetorical Criticism (Chapel Hill: University of North Carolina, 1984). His book presents the categories of ancient rhetoric as someone like the author of Luke-Acts or Hebrews would have likely studied it. It is less certain that Paul would have formally studied rhetoric, although it is not impossible.
 Perhaps the best current book to get into things like what ancient letters looked like and what role secretaries played in writing letters is, E. Randolph Richards, Paul and First-Century Letter Writing: Secretaries, Composition and Collection (Downers Grove: InterVarsity, 2004), another book to add to the fifty some books by which you might master Paul's writings. Another resource is Jerome Murphy-O'Connor's Paul the Letter Writer (Collegeville, MN: Liturgical, 1995).