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).