The First Letter of John has two main purposes: to encourage its readers to live in fellowship with God and with his Son, Jesus Christ, and to warn them against following false teaching that would destroy this fellowship. This teaching was based on the belief that evil results from contact with the physical world, and so Jesus, the Son of God, could not really have been a human being. Those teachers claimed that to be saved was to be set free from concern with life in this world; and they also taught that salvation had nothing to do with matters of morality or of love for others.
In opposition to this teaching the writer clearly states that Jesus Christ was a real human being, and he emphasizes that all who believe in Jesus and love God must also love one another.
Outline of Contents
Light and darkness (1.5—2.29)
Children of God and children of the Devil (3.1-24)
Truth and error (4.1-6)
The duty of love (4.7-21)
Victorious faith (5.1-21)
First John was written to affirm that Jesus is the Christ, to warn believers about false prophets, and to explain basic truths about the Christian life. A special emphasis is placed on the command to love one another.