The title of the fourth gospel continues the pattern of the other gospels, being identified originally as “According to John.” Like the others, “The Gospel” was added later. 

Strategic to John’s background and setting is the fact that according to tradition John was aware of the synoptic gospels. Apparently, he wrote his gospel in order to make a unique contribution to the record of the Lord’s life (“a spiritual gospel”) and, in part, to be supplementary as well as complementary to Matthew, Mark, and Luke.

The gospel’s unique characteristics reinforce this purpose: First, John supplied a large amount of unique material not recorded in the other gospels. Second, he often supplied information that helps the understanding of the events in the synoptics. For example, while the synoptics begin with Jesus’ ministry in Galilee, they imply that Jesus had a ministry prior to that (e.g., Matt. 4:12; Mark 1:14). John supplies the answer with information on Jesus’ prior ministry in Judea (chap. 3) and Samaria (chap. 4). In Mark 6:45, after the feeding of the 5,000, Jesus compelled his disciples to cross the Sea of Galilee to Bethsaida. John recorded the reason. The people were about to make Jesus king because of His miraculous multiplying of food, and He was avoiding their ill-motivated efforts (6:26). Third, John is the most theological of the gospels, containing, for example, a heavily theological prologue (1:1–18), larger amounts of didactic and discourse material in proportion to narrative (e.g., 3:13–17), and the largest amount of teaching on the Holy Spirit (e.g., 14:16, 17, 26; 16:7–14). Although John was aware of the synoptics and fashioned his gospel with them in mind, he did not depend upon them for information. Rather, under the inspiration of the Holy Spirit, he utilized his own memory as an eyewitness in composing the gospel (1:14; 19:35; 21:24).

John’s gospel is the only one of the 4 that contains a precise statement regarding the author’s purpose (20:30, 31). He declares, “these are written that you may believe that Jesus is the Christ, the Son of God, and that believing you may have life in His name” (20:31). The primary purposes, therefore, are two-fold: evangelistic and apologetic. Reinforcing the evangelistic purpose is the fact that the word “believe” occurs approximately 100 times in the gospel (the synoptics use the term less than half as much). John composed his gospel to provide reasons for saving faith in his readers and, as a result, to assure them that they would receive the divine gift of eternal life (1:12).

The apologetic purpose is closely related to the evangelistic purpose. John wrote to convince his readers of Jesus’ true identity as the incarnate God-Man whose divine and human natures were perfectly united into one person who was the prophesied Christ (“Messiah”) and Savior of the world (e.g., 1:41; 3:16; 4:25, 26; 8:58). He organized his whole gospel around 8 “signs” or proofs that reinforce Jesus’ true identity leading to faith. The first half of his work centers around 7 miraculous signs selected to reveal Christ’s person and engender belief: 1) water made into wine (2:1–11); 2) the healing of the royal official’s son (4:46–54); 3) the healing of the lame man (5:1–18); 4) the feeding of multitude (6:1–15); 5) walking on water (6:16–21); 6) healing of the blind man (9:1–41); and 7) the raising of Lazarus (11:1–57). The eighth sign is the miraculous catch of fish (21:6–11) after Jesus’ resurrection.

In accordance with John’s evangelistic and apologetic purposes, the overall message of the gospel is found in 20:31: “Jesus is the Christ, the Son of God.” The book, therefore, centers on the person and work of Christ. Three predominant words (“signs,” “believe,” and “life”) in 20:30, 31 receive constant reemphasis throughout the gospel to enforce the theme of salvation in Him, which is first set forth in the prologue (1:1–18; cf. 1 John 1:1–4) and reexpressed throughout the gospel in varying ways (e.g., 6:35, 48; 8:12; 10:7, 9; 10:11–14; 11:25; 14:6; 17:3). In addition, John provides the record of how men responded to Jesus Christ and the salvation that He offered. Summing up, the gospel focuses on: 1) Jesus as the Word, the Messiah, and Son of God; 2) who brings the gift of salvation to mankind; 3) who either accept or reject the offer.

John also presents certain contrastive sub-themes that reinforce his main theme. He uses dualism (life and death, light and darkness, love and hate, from above and from below) to convey vital information about the person and work of Christ and the need to believe in Him (e.g., 1:4, 5, 12, 13; 3:16–21; 12:44–46; 15:17–20).

There are also 7 emphatic “I AM” statements which identify Jesus as God and Messiah (6:35; 8:12; 10:7, 9; 10:11, 14; 11:25; 14:6; 15:1, 5).