The recognition of the canonical authenticity and the Johannine authorship of this Epistle is similar to that of the Second Epistle. Because of its brevity and private character, the letter did not have a wide geographical distribution; therefore, only a few quotations as to its acceptance are found in the patristic writings. These men recognized its genuineness: Irenaeus, Clement of Alexandria, Dionysius, Cyprian, and Cyril of Jerusalem. The entire church recognized its authenticity at the third Council of Carthage (a.d. 397).

There is a similarity of style and vocabulary between this book and the other three Johannine writings. These distinctive phrases are again seen: "love in the truth," "truth in you," "walk in the truth," and "hath not seen God." The repetition of the author’s self-designated title, "the elder," inseparably links the Third Epistle to the Second. Arguments for the Johannine authorship of one, therefore, can serve for the other as well.

The book was addressed "unto the well beloved Gaius, whom I love in the truth" (1). He was well known not only to John, but also to many Christians and to the church at Ephesus (1, 3, 5–6). But who was he? Gaius was a common name in the first century. Gaius of Macedonia assisted Paul in the apostle’s ministry at Ephesus and was dragged into the ampitheater along with Aristarchus during the insurrection of the pagan silversmiths (Acts 19:29). Gaius of Derbe journeyed with Paul from Macedonia into the province of Asia in the latter months of Paul’s third missionary journey (Acts 20:4). Gaius of Corinth was evangelized and baptized by Paul (1 Cor. 1:14). Later he became Paul’s host and his house became the meeting place of the Corinthian church (Rom. 16:23). The three aforementioned men could all be considered as possibilities for the addressee of this book; however, there is one major problem common to all three. They all were probably converts of Paul, whereas "the well beloved Gaius" seems to have been a convert of John (4). Little is known about this fourth Gaius except that he was an influential, hospitable member of some church in the Roman province of Asia which was under the general spiritual oversight of John. Some have suggested that Gaius was its bishop-elder, but there is no firm support for this conjecture.

Trouble had developed in the church of which Gaius was a member. Diotrephes had usurped authority in the church, speaking ill against John, refusing to receive the apostle’s representatives, and maltreating those who did (9–10). A previous letter sent to the church (either one of the two Epistles or a lost letter) had been totally disregarded by Diotrephes. News of Diotrephes’ audacity reached John either through the return of his emissaries (10), the report of brethren who had been entertained in the home of Gaius (3), or the report of Demetrius (12). John hoped to visit Gaius and the congregation to correct the situation personally, but he was unable to make the trip right away (10, 14). John thus wrote this epistle to encourage Gaius to cope with the situation himself (11). It may be that Demetrius was the bearer of the letter and that John wanted Demetrius to take charge of the work after Diotrephes had been disciplined (12). As with the other Epistles, this letter was penned somewhere in the period between a.d. 85 and 95 by John in Ephesus.

There is an early tradition worth mentioning here. Eusebius claimed that John returned from his banishment on the island of Patmos (Rev. 1:9) to Ephesus after the death of the Roman emperor Domitian in a.d. 96. He further said that John revisited the churches in the province of Asia at that time (cf. 2 John 12; 3 John 14). Because of this tradition, some have suggested that Second and Third John were written after the Book of Revelation. However, these two books could have been written before his exile in Patmos when he still had freedom of movement on the mainland. No one can say with any certainty that John fulfilled his desires to visit the elect lady and Gaius.

In this personal note John determined to inform Gaius of his love and prayers (1, 2), to express his joy over Gaius’ stand for the truth (3, 4), to commend Gaius for his hospitality (5–8), to reveal his displeasure over the arrogance of Diotrephes (9, 10), to promote a rejection of Diotrephes’ leadership and a following of Demetrius’ example (11), to commend Demetrius (12), and to inform Gaius of his plans to visit him (13, 14).

Salutation (1)

Conclusion (13, 14)

As a distinctive signature of his literary style, John again merged the concepts of love, joy, and truth: love in the truth (1), truth in you (3), walk in the truth (3, 4), and fellow helpers to the truth (8). Gaius was not only known for his love (6) but he was greatly loved by all believers and by the apostle himself (1). Gaius may have been a physically weak person because John prayed: "I wish above all things that thou mayest prosper and be in health, even as thy soul prospereth" (2). He was stronger spiritually than he was physically. John then informed Gaius that he was the cause of the apostle’s rejoicing because of his walk in the truth manifested by his hospitality. He commended Gaius not only for entertaining Christian laymen and itinerant missionaries but for giving financial support to them (5–8).

Diotrephes was just the opposite of Gaius. Full of pride, he rejected the apostolic authority of John by disregarding the exhortations of a previous letter, by speaking maliciously about John in public, by not receiving the brethren sent by John, by forbidding those church members who wanted to receive them, and by expelling those members from the church.

John then admonished Gaius to follow that which was good (as personified by Demetrius) and not to follow that which was evil (as personified by Diotrephes). The apostle then declared that Diotrephes was unsaved (11b). He stated that Demetrius had three testimonies to his spiritual goodness: all Christians, the truth itself, and the witness of John. Some have suggested that this was the same Demetrius, the pagan Ephesian silversmith, who persecuted Paul and his companions (Acts 19:23–41). There is no positive equation of the two, but if so, it demonstrates what the grace of God can do in a human life.

John wanted to write more, but since he planned to visit Gaius, he kept the letter short. He then concluded by sending greetings to Gaius and by asking Gaius to greet the apostle’s friends there.