v1-6 - Twice in this section Paul writes, "when we could stand it no longer..." There was no phones, social media, or other communications, and Paul was dying to know how the new Christians in Thessalonica were doing.
Were they being strengthened and encouraged in their faith by Pastor Timothy (v2)?
Or, was there some way the tempter had tempted them, causing them to fall?
v7-10 - When Paul finally hears back, he's encouraged about them because of their faith (v7).
Although life was massively difficult for both Paul and the Thessalonians, Paul thanks God they are "standing firm (v8)."
He prays not for external things to get better, but for a chance to "supply what is lacking in their faith (v10)."
v11-13 - Paul closes this section of the letter with an awesome benediction praying three things for them:
That Paul could come to see them;
For their love to increase and overflow;
That God would strengthen their hearts
There's a ton of things that Paul could have worried about with this fledgling church in Thessalonica. Do they have a good place to meet? Are people giving enough in the offering? Are they having an impact in their community? How can they influence Roman society to be more Christian?
But yet, these questions don't seem to be on Paul's mind at all. The troubles the church faces doesn't surprise them at all, in fact, Paul throws in an "I told you so" in v4.