Excerpt: "In the first three chapters of 1 Thessalonians, Paul's primary concern involved extending compassion and comfort to a suffering and troubled church. There is a gracious, warm, generous tone. He reminds them of how special they are, and how attentive God is to their plight. He reminds them of how God has worked among them in power in the past, he is at work in the present, and he will act again on their behalf through Messiah Jesus at his return. He confesses to them his longing to have close fellowship with them-they are loved and missed.
But Paul's purpose in writing is not purely to offer reassurance and comfort. He also writes to them to remind them of God's expectations for their lifestyle and behavior. It is important for them to know that God has called them into his "glorious kingdom'' (2:12), but this "calling" is also a privilege, a lifelong response and responsibility. They are called to live according to kingdom standards. The constitution of their kingdom citizenship requires holiness, not impurity (4:7). Three main topics are treated in this early section of chapter four: holiness (4:1-8), love (4:9-10), and integrity (4:11-12)."
Gupta, Nijay K., "Exhortation to Persevere and Grow in Holiness, Love, and Integrity (1 Thess 4:1-12) (Chapter in 1 & 2 Thessalonians)" (2013). Faculty Publications - Portland Seminary. 101.