Exegetical Comments on 3 John 5-12
The letter of 3 John is the most letter-like of the three epistles. John identifies himself as the elder (πρεσβύτερος) and identifies the recipient of the letter as Gaius. The identity of Gaius could be related to the figure of 1 Corinthians 1:14 and Romans 16:23, or it could be a different person with the same name. In any case, John is writing to what appears to be a dear friend. The tone of the letter is very personal. The letter to Gaius is an encouragement and a warning about dealing with interpersonal matters in the church.
As evidence of this warmth, John starts Vs. 5 addressing Gaius as Ἀγαπητέ meaning “Beloved” (NASB) or “Dear friend” (CSB). John commends his friend for the work he is doing for people, “especially when they are strangers” (vs. 5b). This commendation of the individual reflects the communal commendation in 2 John – that they are walking in the light and doing the work of Jesus. Gaius’ special commendation for his generous hospitality that was known outside of his community (vs. 6). These “strangers” appear to be missionaries traveling the region (vs. 7). John encourages Gaius to continue his hospitality and support for these folks (vs. 8).
John quickly changes tone in vs. 9 as he warns Gaius about another individual – Diotrephes. This warning is the hub of the letter – what John wants to get to. Diotrephes is guilty of several acts: 1. He loves being first (Vs. 9a directly contradicting Jesus’ warning in Matthew 19:28-29), 2. Reject’s John’s teaching (vs. 9b), 3. Accuses John et al. unjustly (vs. 10a), 4. does not show hospitality to visitors or others in the community (vs. 10b), and 4. put those who do show hospitality out of the church (vs. 10c). John has every intention of calling out Diotrephes when he arrives. Diotrephes is likely a leader of one of the house churches under John’s authority. Whether the conflict is over doctrine, practice, or methodology is lost to history. What is known is that Diotrephes is “simply outright disagreeable,” and he “refuses to accept the authority of John that stands behind the missionaries he backs.”
John finishes this section with encouragement to Gaius to not imitate folks like Diotrephes who has not seen God(vs. 11) but to imitate folks like Demetrius, who does what is good and is of God (vs. 12).
 Tom Wright, Early Christian Letters for Everyone: James, Peter, John and Judah, For Everyone Bible Study Guides (London; Louisville, KY: SPCK; Westminster John Knox Press, 2011), 184.
 John R. W. Stott, The Letters of John: An Introduction and Commentary, vol. 19, Tyndale New Testament Commentaries (Downers Grove, IL: InterVarsity Press, 1988), 230.
 Glenn W. Barker, “3 John,” in The Expositor’s Bible Commentary: Hebrews through Revelation, ed. Frank E. Gaebelein, vol. 12 (Grand Rapids, MI: Zondervan Publishing House, 1981), 373–374.
 Craig S. Keener, The IVP Bible Background Commentary: New Testament (Downers Grove, IL: InterVarsity Press, 1993), 3 Jn 9–11.