Obviously, the second of Paul’s letters to the Thessalonians, and apparently (at least according to the NIV version on the YouVersion Bible App on my phone), it wasn’t written that much longer after the first.
Again, this starts off with thanksgiving for the recipients. Then it goes into the somewhat messy topic of divine justice. It talks about God being just, but a good who also pays back that causes other people’s suffering and the destruction of those who do not know God and do not know the gospel of Jesus. The terms of it are somewhat absolute.
Therefore, Paul continues to pray that God will make the Thessalonians worthy of God’s calling, and that their desires for goodness are realised. Again, it reminds me that God is sanctifying me and that I should desire goodness in accordance with God’s will and he will make me worthy of his calling.