The Doctrine of God John highlights two important characteristics of God. First, God is light (1:5). Second, God is love (4:8). Both of these qualities are essential attributes of God. To walk in the light is to walk in the life of God. To practice love is to demonstrate the character of God.
The Doctrine of Sin First John 3:8 states that the devil is the source of sin, for he “sinned from the beginning.” Sin in the individual is the result of the devil’s hold upon a person, and victory over sin is in reality victory over the devil himself. John describes sin as darkness (1:5–7), lawlessness or rebellion (3:4), and unrighteousness (5:17). Sin is universal and comprehensive. Therefore, every person is a sinner and commits sins (1:8, 10).
The Doctrine of Christology Jesus is presented as the Son of God, and the reality of the incarnation of the preexistent Word is stressed. Twenty-one times Jesus is called the Son in 1 John and twice in 2 John. John states that the Son “was with the Father” and is Himself the “life” of God (1:1–3). Jesus is the “true God and eternal life” (5:20), a direct affirmation of the Son’s deity. He was sinless (3:5), and He made atonement for the sins of the whole world (2:2, 4:10). He destroyed the devil’s work (1 John 3:8), accomplishing all of this by His death (1 John 5:6). His death was a demonstration of the Father’s love (4:9–11) for sinful humanity. He could do all of this because He took on tangible, real human flesh (1:1–3). The incarnation was a true and genuine wedding of perfect deity and sinless humanity.
The Doctrine of the Holy Spirit The Spirit witnesses to the believer concerning the true teaching about Jesus the Christ (2:27; 5:7–8). The Spirit Himself is a gift of anointing. He has been given to the believer (3:24) and enables him to overcome the world (4:4). As the Spirit of truth (4:6), He helps the believer to recognize the false prophets who speak and teach wrongly concerning Jesus.
The Doctrine of Salvation The redemptive work of Jesus Christ has made possible our salvation (2:2; 3:16; 4:10). By believing and receiving the Son (5:10–13) one is born again (5:1), becomes a child of God (3:1–2), and receives the gift of eternal life. Through the new birth we are enabled to do “what is right” (2:29). We may commit individual acts of sin (1:8, 10; 2:1), but we will not habitually live in sin (3:6–9). In salvation God has come to live (abide) in us and we in God (4:15–16).
The Doctrine of Eschatology John lived in the expectancy that the parousia was imminent. He said, “It is the last hour” (2:18). The evidence included the presence of “many antichrists.” John also looked to the eschatological coming of Antichrist as well (2:18; 4:3). John sees the world as already passing away (2:17), indicating that the victory of Christ won at the cross is already underway, yet it awaits a final and climactic consummation. The day of judgment is coming (4:17). Those who live in God and He in them will have confidence in that day and no fear (4:18). When He comes, our transformation will be made complete for “we know that when He appears, we will be like Him, because we will see Him as He is” (3:2). Assured of a right standing before God through faith in His Son who provided atonement for sin, we love God and others, and with this hope in us, we purify ourselves, just as He is pure (3:3).