It has been said that the gospel of John is somewhat like a tract. John's aim is to bring his readers to a faith in Jesus Christ and prove, unequivocally, that He is the Son of God (cf. John 20:30-31). The book is, therefore, separated from what are commonly referred to as the Synoptic Gospels (Matthew, Mark and Luke). These are synoptic in the sense that they are similar in content, order and statement. While the Synoptic Gospels concentrate on the Galilean, Perean and Judean ministry, John speaks at length of the time Jesus spent preaching in Jerusalem. One more distinguishing fact regarding the Gospel of John is that it does not deal with the parables of Jesus as do the Synoptic Gospels.
Another thing that strikes us as odd, while studying the book of John, is that the account of the Lord's Supper is nowhere found. These facts stand as evidence that John had a different purpose in his writing than did the synoptic writers. John's testimony of Christ is given in hope of saving his readers from the current errors being taught of his day (Many believe that when Domitian died in AD 96, John was released from his exile. John returned to Ephesus and there he wrote his gospel, probably around 97 or 98 AD).
Ephesus, being near to Colossi, was subject to the false teachings of Gnosticism, Docetism and Asceticism. Forty years earlier (AD 55), Paul had dealt with a heresy of Asceticism mixed with Gnosticism at Colossi (Colossians 2:20-23). One Gnostic belief was that Simon Peter died on the cross in the place of Jesus. Docetism taught that Jesus never really became incarnate because to do so would be to contaminate His state of deity. Another faction that had reared its head in Ephesus was the belief that John the Baptist was the Messiah. For this cause some knew only the "baptism of John" (Acts 18:24-28; 19:1-7).
As John would have seen these heresies first hand, he determined to write an account of the life of Christ that illustrated proof that Jesus was the Son of God. Secondly, unlike the Synoptic Gospels, John clearly shows the preparatory work of John the Baptist and does not aggrandize him at all. To the contrary, John emphasizes the subordinate function of John the baptizer (John 1:19-28).
Author of the Book of John
The author of the Gospel according to John can be none other than the apostle
The Book of John
John records seven signs that are intended to produce faith in his readers. Eight "I am" statements of Jesus are recorded along with a detailed defense of the deity of Jesus. John focuses much on the teaching of Jesus (i.e., content and style). Jesus preached truth and the terms of admission into the kingdom of God in a pointed (John 5:37ff.) and blunt (John 8:21ff.) style, yet often with care and compassion toward His audience (John 10:11ff.; 11:33ff; etc.). Jesus would ignore irrelevant questions often posed to change the direction of a conversation (cf. John 6:25ff etc.). Jesus gave sharp defenses of the truth (John 18:19ff); however, He always looked to encourage His listeners (John 14:1-2, 18, 27 etc.).
The apostle John deals much with the subject of belief in the epistle. John equates belief with obedience (John 3:36; 5:38), eternal life (6:40, 47), and hearing (4:24). Faith in the gospel is connected with one's ability to know truth (John 7:14ff; 8:31ff; 14:3ff). Lastly, John draws a distinct line between true and pseudo disciples in the book. True disciples abide in the doctrine of Christ (John 5:38; 8:31), partake of truth (John 6:54-68), love (John 13:35; 15:12ff), and bears much fruit (John 15:8)