Paul was showing concern about the early beginnings of the church of Thessalonica, as he was only able to spend roughly six weeks with them. In that concern Paul sent out Timothy to go and visit them and to return to him with a report. While this report was mostly positive there were some misunderstandings that were relevant to the core teachings he left them with. The first parts of the letter address some of these issues by writing on the purity of life and reminding them of why sanctification was important.

1 Thessalonians 1:4-7

[4] Knowing, brethren beloved, your election of God.
[5] For our gospel came not unto you in word only, but also in power, and in the Holy Ghost, and in much assurance; as ye know what manner of men we were among you for your sake.
[6] And ye became followers of us, and of the Lord, having received the word in much affliction, with joy of the Holy Ghost:
[7] So that ye were ensamples to all that believe in Macedonia and Achaia.

Paul was remembering the turnaround of the people and how it was made possible.

1 Thessalonians 2:1-9

[1] For yourselves, brethren, know our entrance in unto you, that it was not in vain:
[2] But even after that we had suffered before, and were shamefully entreated, as ye know, at Philippi, we were bold in our God to speak unto you the gospel of God with much contention.
[3] For our exhortation was not of deceit, nor of uncleanness, nor in guile:
[4] But as we were allowed of God to be put in trust with the gospel, even so we speak; not as pleasing men, but God, which trieth our hearts.
[5] For neither at any time used we flattering words, as ye know, nor a cloke of covetousness; God is witness:
[6] Nor of men sought we glory, neither of you, nor yet of others, when we might have been burdensome, as the apostles of Christ.
[7] But we were gentle among you, even as a nurse cherisheth her children:
[8] So being affectionately desirous of you, we were willing to have imparted unto you, not the gospel of God only, but also our own souls, because ye were dear unto us.
[9] For ye remember, brethren, our labour and travail: for labouring night and day, because we would not be chargeable unto any of you, we preached unto you the gospel of God.

What was the full substance of Paul’s ministry? What did they bring? What did they do?

1 Thessalonians 3:1-6

[1] Wherefore when we could no longer forbear, we thought it good to be left at Athens alone;
[2] And sent Timotheus, our brother, and minister of God, and our fellowlabourer in the gospel of Christ, to establish you, and to comfort you concerning your faith:
[3] That no man should be moved by these afflictions: for yourselves know that we are appointed thereunto.
[4] For verily, when we were with you, we told you before that we should suffer tribulation; even as it came to pass, and ye know.
[5] For this cause, when I could no longer forbear, I sent to know your faith, lest by some means the tempter have tempted you, and our labour be in vain.
[6] But now when Timotheus came from you unto us, and brought us good tidings of your faith and charity, and that ye have good remembrance of us always, desiring greatly to see us, as we also to see you:

Why did Paul send Timothy back from Athens back to them? There was a great concern in his heart for them.

1 Thessalonians 4:4-14

[4] That every one of you should know how to possess his vessel in sanctification and honour;
[5] Not in the lust of concupiscence, even as the Gentiles which know not God:
[6] That no man go beyond and defraud his brother in any matter: because that the Lord is the avenger of all such, as we also have forewarned you and testified.
[7] For God hath not called us unto uncleanness, but unto holiness.
[8] He therefore that despiseth, despiseth not man, but God, who hath also given unto us his holy Spirit.
[9] But as touching brotherly love ye need not that I write unto you: for ye yourselves are taught of God to love one another.
[10] And indeed ye do it toward all the brethren which are in all Macedonia: but we beseech you, brethren, that ye increase more and more;
[11] And that ye study to be quiet, and to do your own business, and to work with your own hands, as we commanded you;
[12] That ye may walk honestly toward them that are without, and that ye may have lack of nothing.
[13] But I would not have you to be ignorant, brethren, concerning them which are asleep, that ye sorrow not, even as others which have no hope.
[14] For if we believe that Jesus died and rose again, even so them also which sleep in Jesus will God bring with him.

Paul begins to address some of the weaknesses through exhortation.

1 Thessalonians 5:14-24

[14] Now we exhort you, brethren, warn them that are unruly, comfort the feebleminded, support the weak, be patient toward all men.
[15] See that none render evil for evil unto any man; but ever follow that which is good, both among yourselves, and to all men.
[16] Rejoice evermore.
[17] Pray without ceasing.
[18] In every thing give thanks: for this is the will of God in Christ Jesus concerning you.
[19] Quench not the Spirit.
[20] Despise not prophesyings.
[21] Prove all things; hold fast that which is good.
[22] Abstain from all appearance of evil.
[23] And the very God of peace sanctify you wholly; and I pray God your whole spirit and soul and body be preserved blameless unto the coming of our Lord Jesus Christ.
[24] Faithful is he that calleth you, who also will do it.

This was Pauls closing remarks and were a very important section of the letter, especially for us today.