The Apostle John tells us that he wrote the book of 1 John so that believers may know that they have eternal life. (5:13) This letter is an examination of who Jesus is and why he came, in human form, to dwell among those He created. 

John was the best friend of Jesus - he knew our Savior personally. There is no one better qualified to pass along a robust understanding of Jesus' love and purpose for his people.