John’s three letters are books in the New Testament. The writer of these books is John, an apostle of Jesus Christ. In his letters, he preaches love and encourages people to be steadfast on the true path. He tells people to love each other and that a brother should not kill his brother like Cain killed Abel. John says that the meaning of true love is to follow the teachings of Christ. He tells the believers to differentiate between good and the evil and abstain from sinful deeds.