A fitting conclusion: Exhortation and Encouragement.

1 John 5:16-21

First Exhortation - We must be vigilant and discerning in our relationships (vss. 16-17).

First Encouragement - Jesus protects His people and enables us to live a life of repentance and faith (vs. 18).John 10

John 17:10-19

Therefore, my beloved, as you have always obeyed, so now, not only as in my presence but much more in my absence, work out your own salvation with fear and trembling, for it is God who works in you, both to will and to work for his good pleasure. - Philippians 2:12–13(ESV)

Second Encouragement - We have been rescued from Satan’s kingdom and have been transferred into God’s (vs. 19).
Giving thanks to the Father, who has qualified you to share in the inheritance of the saints in light. He has delivered us from the domain of darkness and transferred us to the kingdom of his beloved Son, in whom we have redemption, the forgiveness of sins. - Colossians 1:12-14(ESV)

Third Encouragement - We have been renewed to vital, intimate union with God (vs. 20).
For the law was given through Moses; grace and truth came through Jesus Christ. No one has ever seen God; the only God, who is at the Father's side, he has made him known. - John 1:17–18(ESV)

John 17:20-23

Second Exhortation - We must be vigilant and discerning in regard to our affections (vs. 21).
Keep your heart with all vigilance,
for from it flow the springs of life. - Proverbs 4:23 (ESV)