We have come to the end of the "theological" portion of 1 Thessalonians. Paul, in introducing the "practical" outworking of doctrine, urges the Thessalonian Christians generally to keep going in godliness.
This structure of Paul's teaching is found in many of his epistles or letters. The Westminster Assembly in Britain in the 1600s picked this up, and used it in one of their questions and answers in the Shorter Catechism: "Q. 3 What do the Scriptures principally teach? A. 3 The Scriptures principally teach, what man is to believe concerning God, and what duty God requires of man." Our poor pastor rather stumbled on this in this sermon, but has it re-memorized now!