This coming Sunday we begin a several-weeks reading through First Thessalonians. It's fascinating, for one because, being Paul's earliest extant writing, it shows his soteriology at least early in his ministry.
Paul was an apocalypticist who believed the End of Days was near when God would send the Son of Man (Daniel 7) to overthrow earthly powers and establish the Kingdom of God on Earth.
This would be heralded by the General Resurrection with the Second Coming of Christ as that Son of Man, when all dead and living (Paul expected to be among the living, it was that imminent) would be raised and lifted into the clouds to meet Christ for judgment.
Those under the umbrella of the faith of Christ, and whose lives passed judgment, would be saved into the new Kingdom of God on Earth, with Christ the Son of Man as God's regent.
The letter that we call First Thessalonians was meant to be read to its intended audience (members of the church in Thessalonica that Paul had founded), aloud in its entirety (not in the snippets, bits and pieces that we read on Sunday mornings).
Paul evidently wrote it because word had come to him that the Thessalonians were becoming disenchanted with the gospel he had preached (Second Coming immediately) because some members of the church had died and the End Time had not yet come (it still hasn't come). Paul wrote to assure them that those who had died would not miss out, that they would be raised and included when still-imminent End Time came.
This is called an "occasional" letter, and the occasion for Paul's writing was to give worried members of the Thessalonians church that assurance over against their anxiety and doubts.
BTW, of the thirteen canonical letters in what's called the Pauline corpus (body of letters), only seven are generally accepted as genuinely written by Paul. First Thessalonians is the first of those. The others are First and Second Corinthians, Galatians, Philippians, Philemon, Romans.
The purpose of the map above is to show where Thessaloniki was/is in Paul's Time. (I keep typing Thessalonica but spell check keeps correcting it to Thessaloniki).
Below is the reading for the upcoming Sunday.
RSF&PTL
T91
1 Thessalonians 1:1-10
Paul, Silvanus, and Timothy, To the church of the Thessalonians in God the Father and the Lord Jesus Christ:
Grace to you and peace.
We always give thanks to God for all of you and mention you in our prayers, constantly remembering before our God and Father your work of faith and labor of love and steadfastness of hope in our Lord Jesus Christ. For we know, brothers and sisters beloved by God, that he has chosen you, because our message of the gospel came to you not in word only, but also in power and in the Holy Spirit and with full conviction; just as you know what kind of persons we proved to be among you for your sake. And you became imitators of us and of the Lord, for in spite of persecution you received the word with joy inspired by the Holy Spirit, so that you became an example to all the believers in Macedonia and in Achaia. For the word of the Lord has sounded forth from you not only in Macedonia and Achaia, but in every place your faith in God has become known, so that we have no need to speak about it. For the people of those regions report about us what kind of welcome we had among you, and how you turned to God from idols, to serve a living and true God, and to wait for his Son from heaven, whom he raised from the dead-- Jesus, who rescues us from the wrath that is coming.