New Testament

3 John

Third John is a short personal letter from 'the elder' to his friend Gaius, praising him for welcoming traveling missionaries, rebuking a church leader named Diotrephes who refused them and put out those who welcomed them, and commending a man named Demetrius. It is the shortest book in the Bible by word count in the Greek. It belongs in Scripture because it shows how ordinary church hospitality advances the truth and how ambition for position harms the church.

Author: 'The elder' (1:1), traditionally the apostle John, the same writer as 2 John. As with 2 John, some scholars identify the elder as a different leader named John known in Asia, but the style closely matches 1 and 2 John.
Audience: 'The beloved Gaius' (1:1), a believer in a church where Diotrephes held influence. Gaius was a common name, so he cannot be identified with confidence with any other Gaius in the New Testament.
When: Probably in the late first century, about the same time as 1 and 2 John, around AD 85–100.
Where: Not stated. Tradition places the elder in or near Ephesus, writing to a nearby church in Asia.
Genre: Third John is a private letter in the standard ancient form, short enough for a single sheet of papyrus, and it opens with a conventional wish for good health (1:2). Read it as a window into everyday church life in the first century: traveling preachers, letters of commendation, local power struggles and the practical support of mission. Its brevity means much must be inferred, so read the relationships carefully.

Shape of the book

Greeting and Joy Over Gaius · ch 1Verses 1–4: The elder greets Gaius, wishes him well, and rejoices to hear that he walks in the truth.
Support for the Missionaries · ch 1Verses 5–8: Gaius is commended for faithfully welcoming brothers who were strangers and urged to send them on in a manner worthy of God, since supporting them makes us fellow workers for the truth.
Diotrephes and Demetrius · ch 1Verses 9–12: Diotrephes, who loves to be first, rejects the elder's authority and refuses the brothers, while Demetrius is commended by everyone and by the truth itself.
Closing Hope and Greetings · ch 1Verses 13–14: The elder hopes to speak face to face soon and sends greetings between friends by name.

Themes

Walking in the Truth. The elder's greatest joy is to hear that his children are walking in the truth (). Truth here is not only a set of beliefs but a way of life shaped by them, and Gaius's love for the brothers is evidence of it (, ).
Hospitality as Partnership in Mission. Missionaries went out 'on behalf of the Name, accepting nothing from the Gentiles' (). Believers who welcome and send them on become fellow workers for the truth (). Practical support of gospel workers is itself gospel work.
Ambition That Divides. Diotrephes 'loves to be first' (). He slanders the elder, refuses the brothers and puts out those who would welcome them (). The letter exposes self-seeking leadership as a danger to the church, whether or not his teaching was wrong.
Imitating the Good. Do not imitate what is evil, but what is good (). The one who does good is of God; the one who does evil has not seen God. Demetrius, well spoken of by all, is offered as the good example ().

Where Christ is

Third John never uses the names Jesus or Christ, so its connection to Him is indirect. The missionaries go out 'on behalf of the Name' (), almost certainly the name of Jesus, and the 'truth' that the elder loves is, in John's writings, embodied in Christ (). The letter's picture of servant leadership stands in contrast to Diotrephes and in line with Jesus' teaching.

For the Sake of the Name. Echo. The early church spoke of suffering and serving 'for the Name' (), meaning the name of Jesus, which God exalted above every name (). Third John uses the same shorthand for the missionaries' cause. (; ; )
The Truth Embodied. Echo. The elder writes of walking in the truth and being fellow workers for the truth (, ). In John's Gospel, Jesus calls Himself the truth () and promises the Spirit of truth. (; ; )
Receiving Those He Sends. Echo. Jesus taught that whoever receives those He sends receives Him (; ). Gaius's welcome of the traveling brothers, and Diotrephes' refusal, take on weight in that light. (; ; )

Reading well, key terms and common misreadings

Read it well

Read it together with 2 John. One warns against supporting false teachers; this one commends supporting true ones.
Picture the people: Gaius the generous host, Diotrephes the controlling leader, Demetrius the trusted man who may have carried the letter, and traveling brothers who depend on hospitality.
Notice what is not said. The letter does not state that Diotrephes taught false doctrine; his fault as described is pride and refusing fellowship.

Key terms

Send on one's way προπέμπω (propempō) — To equip and help a traveler continue his journey, often with food, money and companions (1:6). It was a standard way the early church supported missionaries (Romans 15:24; Titus 3:13).
Fellow worker συνεργός (synergos) — A co-worker. Those who support missionaries share in their work for the truth (1:8).
Loves to be first φιλοπρωτεύω (philoprōteuō) — A rare word meaning to love having first place (1:9), describing Diotrephes' ambition.
Witness, testify μαρτυρέω (martyreō) — To bear witness. The brothers testify about Gaius (1:3, 1:6), and Demetrius has good testimony from everyone and from the truth itself (1:12).

Easy to misread

Taking 1:2, the wish that Gaius may prosper and enjoy good health, as a promise that God guarantees wealth and health to believers. It is a conventional opening wish in ancient letters, expressed as the elder's prayer for a friend.
Assuming Diotrephes was a heretic. That may be so, but the letter faults his love of first place, his slander and his refusal of hospitality, which shows these sins harm a church even when doctrine is not named as the issue.
Dismissing the letter as too personal to matter. Its inclusion in Scripture shows that hospitality, support for missionaries and humble leadership are part of walking in the truth.

Further reading: David Guzik, Enduring Word · Matthew Henry on CCEL · BibleProject overview video