John the Apostle wrote the Gospel that bears his name, and especially in his first letter, he enlarges in summary form, his conclusions about Jesus Christ, and his personal involvement as a witness to his glory: “That which was from the beginning, which we have heard…seen with our own eyes…which we have looked at and our hands have touched….” Compare that with John 1:14— “And the Word became flesh and dwelt among us, and we beheld his glory….” John is also fighting the unseen enemy of Gnosticism. Speaking of Christ’s actual life on this earth. He later speaks of the spirit of Antichrist (2:18-27 and references in later verses). But he also desires to bring assurance to believers, to help them know that they are “saved” (see 5:11-13). Perhaps the theme of the book is fellowship with God, the nature of which he describes as light, love and life. And the loving behavior which Christians should exhibit in relationships with one another is a major theme in I John.
Here is an outline for I John:
I. Introduction and purpose of the letter (1:1-4)
II. Conditions vital for fellowship (1:5-2:2)
III. Conduct consistent with fellowship (2:3-27)
IV. Characteristics of fellowship (2:28-5:3)
V. Consequences of fellowship (5:4-21)