Identifying and defending the authorship of the Gospel of John is important from the standpoint of defending the faith because John is a fairly early source of first hand information about the life of Jesus. Particularly in light of John’s close relationship with Christ. John is a powerful tool in responding to critics. If a Christian is to defend the author of the gospel, he/she needs to know what support exists for John’s authorship, as many unbelievers challenge apostolic authorship. In the case of John this is generally based on skepticism and no facts.

Though probably written last, the gospel was still likely written before 80 AD. I argue this position because of the treatment of the Temple in the text. The temple was likely still standing or recently destroyed when the book was written based on two factors.

  1. The gospel seems to treat the temple as a structure that still stood and doesn’t mention its having been destroyed. In addition, it demonstrates intimate knowledge of the city of Jerusalem, which suggests that the author had been there recently or lived there for some time. This would require a pre-70 AD authorship.
  2.  There are those that argue that Jesus is juxtaposed to the temple in such a way as to hint that the author may be suggesting to Jewish readers that Jesus is the replacement for the recently destroyed temple. This would require that the temple be gone, which would place the date after 70. However, if John is referring to the temple, he does so without words. This gentle discussion of the matter lends to a relatively close date to the destruction of the temple, which would require increased delicacy. However, enough time would have had to pass for word to get around. This points to 80 AD as late date for authorship.

John is also important because it is generally accepted that it was written in aramaic, which was probably Jesus’ native language. The fact that it was written in aramaic closely associates the book with Israel and bolsters the case for its accuracy as an eye witness account.

Determining the authorship of John’s Gospel requires consideration of both internal and external evidence.

Internally, we see that the narrator identifies himself as an apostle. In both 1:14 and 2:11 John identifies himself amongst the disciples by using the pronoun “we.” This suggests that the author was one of the disciples present. 21:20 indicates that “the disciple who Jesus loved” is the author as well, because he refers to the anonymous disciple and then indicates that he is the writer of the book in verse 24.

The last supper offers further evidence for the elimination of several names from the list of candidates. The disciple identifies himself as present and reclining on Christ’s breast during the meal. He also mentions: Peter, Philip, Thomas, Judas Iscariot and Judas the son of James. These men could not be the author because he would scarcely have mentioned them by name and himself anonymously. In addition, we can eliminate several additional names through the account of the 7 disciples fishing in 21:2. This includes: Simon Peter, Thomas and Nathanial. In addition, 21:2 mentions the sons of Zebedee and two other disciples, which are acceptable candidates because of their lack of specific naming. James the son of Zebedee cannot be a potential candidate because of his early martyrdom (42 AD).

The remaining disciples are: Matthew, Simon the Zealot, James son of Alphaeus and John son of Zebedee. Matthew is unlikely because he is credited with writing another gospel. Simon the Zealot and James son of Alphaeus are both obscure figures and have never been suggested as authors. This leaves John the son of Zebedee.

John is a strong candidate because of his close proximity to Peter in several accounts in the synoptic gospels, which coincides with the frequent close proximity of Peter to the Disciple that Jesus loved. Ultimately, John the son of Zebedee is the only disciple that has such close proximity to Peter (other than James who is not appropriate because of his early death).

Interestingly, John’s gospel is silent on the inner circle of Christ’s followers. This supports Johannine authorship because of the anonymous nature of the text. John could scarcely have mentioned it without tipping his hand as to his identity. In addition, it accounts for the author’s prominent role within the text of John.

It is important to note that John’s familiarity with Jesus and its anonymity offering interesting hints as to authorship. If the book was not written by John, then the author would likely have not hidden his identity only to leave enough clues in the text for the reader to figure out that John was the author. If the author was to forge a text in John’s name, wouldn’t it be more reasonable to use John’s name. The purpose of usurping an apostle’s name is notoriety. This is defeated in hiding the identity of the author.

External evidence comes from the church father Irenaeus, who used the gospel in his refutation of the early gnostic heresies. Irenaeus claims to have learned from Polycarp, who was himself a disciple of John. Irenaeus goes further and identifies John as the disciple who reclined on Christ during the last supper.

Church father Clement of Alexandria also identifies the apostle John as the author of the gospel as well. After the end of the second century church tradition is unanimous on the matter of authorship.