Author

The book is without autograph but it was unquestionably the work of the Apostle John, likely written near the end of the first century, perhaps in the 80s A.D. First, the numerous phrases found in the book are common to both this letter and the Gospel of John.  

• “To walk in darkness” (compare 2:11 to John 8:12)

• “Children of God” (compare 3:2 to John 11:52)

• “To be born of God”  (compare 3:9 to John 1:13)

• “The Spirit of truth” (compare 4:6 to John 14:17; 15:26; 16:13)

• “The only begotten Son” (compare 4:9 to John 3:16) 

• “The Savior of the world” (compare 4:14 to John 4:42)

• “Water and the blood” (compare 5:6 to John 19:34)

Second, the author was an eyewitness to Jesus’ death and Resurrection (1:1).

Audience

Irenaeus, an early church father, claimed John gave the latter years of his life to the church at Ephesus as the overseer. John, aware that false teachers had intruded into the church (Acts 20:29-30), and having convinced some believers to withdraw from the fellowship, wrote this letter to correct the problem among the Ephesian believers.  

Their false teaching centered around two heresies concerning the Person of Christ—one group denied Jesus as the Christ (2:22), and the other group denied Jesus had come in the flesh (4:2-3).

Whenever the Person of Jesus is threatened, all kinds of problems arise, because denying who Jesus is ultimately evolves into a denial of His sovereign Lordship. So, the Ephesians were developing a tendency toward lustful lifestyles (2:15-17), leading to denying they were sinning at all (1:5-2:6).

Purpose

The obvious reason John wrote the book was to correct false teaching, which was leading to false practices, specifically the false teaching concerning the Person of Jesus. His desire in correcting the errors was to restore the assurance of the believer. Affirming that, John used the phrase, “we know,” thirteen times (2:3, 5, 29; 3:14, 16, 19, 24; 4:13, 16; 5:15, 18, 19, 20). The whole book was developed around the theme of convicting the hearts of those who had put their faith in Christ. John wanted every one of them fully assured that it was the work of the true Christ that had changed them. The work of salvation had deeply changed who they were.

John wrote his Gospel to create faith in Jesus Christ so those who believed would experience life (John 20:31). John wrote this letter (1 John) to give those who believe the assurance that their faith was genuine, from God, leading them to possess eternal life (5:13).