We use the name “John” as shorthand for the gospel itself. But who is the person behind the name? None of the Gospels is signed. Today’s gospel titles—the Gospel According to John (or Matthew or Mark or Luke)—are late additions. The closest we come to an author’s signature in any of the Gospels appears near the end of John’s text:

“And there stood by Jesus’ cross his mother and his mother’s sister…So Jesus, seeing his mother and the disciple whom he loved standing by, said, ‘Woman, look: here is your son.’ Then he said to the disciple: ‘Look, here is your mother.’ And from that hour the disciple took her into his own home” (John 19:25–27). The story continues: Jesus dies. He and the other crucified men must be removed before the sun sets and the Sabbath begins. To hasten the victims’ deaths, the soldiers break the legs of the men on either side of Jesus. The soldiers see that Jesus is already dead. One of them drives a spear into his side; blood and water gush out. Then we read: “He who saw this has testified to it, and his testimony is truthful, and that man knows that he speaks the truth, so that you too might believe” (John 19:35).

The author is emphatic: This is an eyewitness account. Clearly, the writer wanted his readers to believe his account of the death was accurate and should be believed. But who was this eyewitness?

“It is notorious,” wrote the late New Testament expert Raymond E. Brown, “that many biblical scholars are passionate readers of detective stories. These two interests come together in the quest to identify the author of the Fourth Gospel.”1 The first clues are easy to find: The disciple Jesus loved was standing beneath the cross; so was the eyewitness. Many readers have thus concluded they were one and the same.

The gospel’s final chapter, chapter 21, which tells of the resurrected Jesus, strengthens the case for the involvement of the beloved disciple, even though this chapter is frequently identified as an appendix by a separate or later author.2 In this chapter, Jesus has just reappeared to the disciples on the shores of the Sea of Galilee and has commissioned Peter to “tend [his] sheep” and “feed [his] flocks” (John 21:15–17). Peter points out “the disciple Jesus loved, who had reclined next to Jesus at the supper” (a reference to John 13:23–25), and asks Jesus, “What about him?” Jesus replies: “If it is my will that he remain until I come, what is that to you?” (John 21:22). The gospel concludes, “This [the beloved disciple] is the disciple who is testifying about these things and who wrote them, and we [his own disciples, who preserved the work] know that his testimony is true” (John 21:24). The author of this last chapter is believed to have been a member of the beloved disciple’s community. He clearly identifies the beloved disciple as the witness whose testimony is preserved throughout the entire gospel.

By the end of the second century this beloved disciple had been given the name John.

Writing around 190 C.E., St. Irenaeus of Lyons tells us that this John lived at Ephesus until the reign of Emperor Trajan (98 to 117 C.E.). Irenaeus learned about John through St. Polycarp (died c. 155), who claimed to have spent time with John as a young man.

“Later John the Lord’s pupil,” Irenaeus wrote, “who reclined on the Lord’s chest, himself published the gospel while staying at Ephesus in Asia.”3 It is difficult to evaluate Irenaeus’s account, however, especially because he did muddle his memories of Polycarp elsewhere. He may well have been right about the name, but who was this John? Was he Jesus’ close disciple “John the son of Zebedee,” who, according to Luke, was the brother of the disciple James and Peter’s fishing partner (Luke 5:3)? Or was he another of Jesus’ followers?4 Or was he John of Patmos, the author of the Book of Revelation? (And which John was that? There’s another complex question!)

Who was the beloved disciple who wrote the Gospel of John? We will probably never have a clear answer. But scholars, like any eager sleuths, will never let the mystery be.