The theme of John’s letters, like James’, Peter’s, and Jude’s, reflect on two problems in the early church: love for others and false teaching. John begins chapter 1 with his testimony of actually having been with God in the flesh, Jesus Christ the eternal Son Who brought eternal life to us. He continues this theme through chapter 2 verse 6.
In chapter 2 verses 7-17, John contrasts loving other Christians with loving the things of the
world. Then in verses 18-27, John writes about the many anti-christs in the world in their day. Some of these people were claiming that the man Jesus was not really God.
From chapter 2 verse 28 through chapter 3, John writes about how much God loves us by calling us His children. Now, because God loves us so much, we should be loving our brothers and sisters the same way.
Chapter 4 begins with instructions about how to discern a false prophet from a true one, and it revolves around what they say about Jesus Christ. Beginning in verse 7, John provides another lesson about love.
Chapter 5 gives more evidence of how love is evident in the lives of believers plus more teaching on the identity of Christ as the Son of God. John goes on with his conclusion by giving the reason for his letter that is also the key verse. “I have written this to you who believe in the name of the Son of God, so that you may know you have eternal life.” 1 John 5:13 NLT.