Purpose and Audience
The purpose of the Gospel of John is stated in John so luckily there can not be much debate on purpose for John writing this book. John 20:31 says, “but these are written so that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name.” This is why the confession of Martha is so extremely central to this book, the whole book until that point people are saying different things about Jesus, but when we get to John 11:27 Martha almost verbatim says what John says in 20:31 as his purpose for writing it. While how this verse is translated in most of our major translations (NIV. NASB. NRSV. ESV) all translate 20:31 similarly, there is another way to translate this verse. How all of these translations translate the verse makes it seem this book is for evangelism. However, a better translation to better reflect the most probable purpose of the Gospel would be, “so that you may keep believing that Jesus is the Christ, the Son of God…” This second form suggests that the gospel was written to encourage the persecuted church. Which is the most likely purpose for this book.
The best evidence we have towards finding an exact target audience, date, and place authored of the Gospel of John is Irenaus, who claimed that John wrote his gospel while in Ephesus. Ephesus was a pupil of Polycarp who knew John personally.
Authorship
The strongest external evidence of John the Son of Zebedee’s authorship is Irenaeus' statement, “Afterwards, John, the disciple of the Lord, who also had leaned upon His breast, did himself publish a Gospel during his residence as Ephesus in Asia.” Other external evidence includes the Muratorian Fragment, and the Clement of Alexandria as cited in Eusebius. It is important to note that none of these claim that they are specifically talking about the son of Zebedee. However, of the twelve there is only one mentioned named John, and if we are taking the link to Polycarp as solid evidence then the Son of Zebedee is the author.
Sources
Irenaeus of Lyons, “Irenæus against Heresies,” In The Apostolic Fathers with Justin Martyr and Irenaeus, edited by Alexander Roberts, James Donaldson, and A. Cleveland Coxe, Vol. 1. The Ante-Nicene Fathers. Buffalo, NY: Christian Literature Company, 1885, Logos Bible Software version 10, 2023, Iren., Adv. Haer. 3.1.1.
Raymond E. Brown, The Gospel according to John (I–XII): Introduction, Translation, and Notes, Vol. 29, Anchor Yale Bible, New Haven; London: Yale University Press, 2008, Logos Bible Software Version 10, 2023 Page lxxxviii
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