While the author’s name is not found in the letter, it has traditionally been ascribed to John the apostle. Various references by early Christian writers including Irenaeus, Clement of Alexandria, and Tertullian spoke of John as the author of this epistle. From the standpoint of internal evidence, there are some stylistic differences from the gospel of John, but these can be attributed to the differences between an epistle and a gospel. Further, many similarities exist by way of key words (abide or remain) or contrasting figures like righteousness and sin, light and darkness, life and death, love and hate, and truth and error. In addition, the writer was one of the original witnesses of the Savior who knew Him intimately (1:1-5). Then there are many similar expressions and phrases: compare 1 John 1:1 with John 1:1, 14; 1:4 with John 16:24; 1:6-7 with John 3:19-21; and 4:9 with John 1:14, 18; 3:36. There are no good reasons why this book should not be attributed to the apostle John.
Though it is generally agreed that the same person wrote the gospel of John and these three epistles, some feel that they were not written (as traditionally held) by John the apostle, the son of Zebedee, but by another John (the elder or presbyter, 2 John 1; 3 John 1). It is argued that (1) an uneducated man (Acts 4:13) could not have written something so profound as this gospel; (2) a fisherman’s son would not have known the high priest as did John the apostle; and (3) an apostle would not have called himself an elder. But “uneducated” did not mean illiterate, only without formal training in the rabbinic schools; some fishermen were well-to-do (cf. Mark 1:20); and Peter, though an apostle, called himself an elder (1 Peter 5:1). Further, if John the elder is the “beloved disciple” and the author of the gospel, why did he not mention John the son of Zebedee, an important figure in the life of Christ, in that gospel? Every evidence points to John the elder being the same as John the apostle and the author of this letter.
All the way through the epistle there are verses that indicate John was writing to believers (2:1, 12-14, 19; 3:1; 5:13), but John nowhere indicates who they were or where they lived. This fact may suggest it was a circular letter to be circulated among several churches, perhaps around the city of Ephesus since early Christian writers placed #2John at Ephesus in his later years.
The earliest confirmed use of 1 John was in the province of Asia (in modern Turkey), where Ephesus was located. Clement of Alexandria indicates that John ministered in the various churches scattered throughout that province. It may be assumed, therefore, that 1 John was sent to the churches of the province of Asia.
It is difficult to precisely date this and the other epistles of John, but since many of the themes and words are so similar to the gospel of John, it is reasonable to assume it was written after the gospel. It was undoubtedly written after the gospel but before the persecutions of Domitian in A.D. 95. Therefore, a reasonable date is somewhere between A.D. 85-90.
The theme of the book is fellowship with God through the Lord Jesus (1:3-7). In view of the heresy facing these believers, perhaps an early form of gnosticism, John wrote to define the nature of fellowship with God whom he describes as light, love, and life. God is light (1:5), God is love (4:8, 16), and God is life (see 1:1-2; 5:11-13). To walk in fellowship with God, then, means to walk in the light which leads to experiencing His life, His love for others, and His righteousness. The book, then, gives a number of tests or proofs of fellowship, though some see these as tests of salvation. But in keeping with the theme, the teaching of the false teachers, and the nature of his audience as believers, it is best to view these as tests or proofs of fellowship, tests of abiding and knowing the Savior in an intimate relationship that experiences the transforming life of the Savior in believers.
The exact form of the heresy facing these Christians is difficult to determine, but from the content of 1 John it involved denial of the reality of the incarnation and a claim that sinful behavior did not hinder fellowship with God. Thus, John wrote to his “little children” (2:1, 18, 28; 3:7, 18; 5:21) for at least five reasons: (1) to promote true fellowship (1:3f.), (2) to experience full joy (1:4), (3) to promote holiness through true fellowship (1:6-2:2), (4) to prevent and guard against heresy (2:18-27), and (5) to give assurance (5:11-13).
The key concept is fellowship as expressed in the terms fellowship (1:3, 6, 7), and abide, abiding, etc. (2:6, 10, 14, 17, 27, 28; 3:6, 9, 14, 15, 17, 24; 4:12, 13, 15, 16). Other key words are righteous, righteousness, light, darkness, and sin and lawlessness.
Surely, one of the key passages in 1 John, and even in the New Testament, is chapter 1 because of its truth regarding sin, even in the life of the Christian. To walk in the light means an honest acknowledgment of the problem of sin. Rather than the denial of sin, this chapter shows us the need for the confession of the principle of sin (1:8), confession of particular or personal sins (1:9), and confession of the practice of sin (1:10).
This book focuses on the present ministry of the Savior in the life of believers and anticipates His coming again. His blood continually cleanses the believer from all sin (1:7) and from personal sins and all unrighteousness upon confession of sin (1:9). Indeed, it declares that Christ is our righteous Advocate before the Father (2:1) and the propitiation or atoning sacrifice not only for believers, but for all the world (2:2), that Jesus is the Christ who has come in the flesh (2:22; 4:2-3), that He came by water and by blood, a reference to His baptism and the cross (5:6), and that He is coming again when we shall see Him and be like Him (2:28-3:3).