3 John —the second-shortest book of the Christian Bible by number of verses and shortest in regard to number of words (according to the Authorized King James Version)— is written by a man identified only as "the presbyteros".
While the letter is addressed to Gaius (Caius), scholars are uncertain if this Caius is the Christian Caius in Macedonia (Acts 19:29), the Caius in Corinth (Romans 16:23) or the Caius in Derbe (Acts 20:4) is the intended recipient.
Indications within the letter suggest a genuine private letter, written to commend to Gaius a party of Christians led by Demetrius, who were strangers to the place where he lived, and who had gone on a mission to preach the gospel (verse 7). The purpose of the letter is to encourage and strengthen Caius, and to warn him against the party headed by Diotrephes, who refuses to cooperate with the presbyteros who is writing.
de Jong argued for a date of 100-110 AD, due to the Epistles links with Ignatius and Polycarp, while Marshall suggests a date of between the 60s and 90s. Rensberger suggests a dating of around 100 for the Johannine Epistles, on the basis that the Gospel of John was written in the 90s. Brown has also argued for a date of between 100 and 110 with all three epistles being written in close proximity. A date later than 110-115 is thought unlikely as parts of the first two Epistles were quoted by Polycarp and Papia. Additionally Marshall cautions that greater precision in dating is unwelcome due to that lack of more precise evidence.
Church tradition has placed all the Johannine Epistles in Ephesus, although the letters themselves do not implicitly support or contradict this opinion, the Gospel of John has internal and external evidence suggesting Ephesus. The first knowledge of the letters comes from the area of Asia Minor, which does perhaps support the Ephesus hypothesis. Both 2 and 3 John refer to travelling, implying that the communities may not have been in the same location, although that would have had to be in the same general vicinity. Additionally the teaching opposed in 1 John may link that letter with Cerinthus, which by extension to the other Epistles, may link them to Ephesus.
Nuack proposed linking the Epistles to Syria, however his interpretation is not generally accepted, and the evidence is considered weak.
The first reference to 3 John is in the middle of the third century; Eusebius says that Origen knew of both 2 and 3 John, however Origen is reported as saying "all do not consider them genuine. Similarly, Dionysius of Alexandria, Origen's pupil, was aware of a "reputed Second or Third Epistle of John." Also around this time 3 John is thought to have been known in North Africa as it was referred to in Sententiae Episcoporum, produced by the Seventh Council of Carthage.
There was also doubt about the authority of 3 John, with Eusebius listing it and 2 John as "disputed books" despite describing them as "well-known and acknowledged by most." Although Eusebius believed the Apostle wrote the Gospel and the epistles, it is likely that doubt about the fidelity of the author of 2 and 3 John was a factor in causing them to be disputed. By the end of the fourth century the Presbyter (author of 2 and 3 John) was thought to be a different person to the Apostle John. This opinion, although reported by Jerome, was not held by all, as Jerome himself attributed the epistles to John the Apostle.
All three Johannine epistles were recognised by the 39th festal letter of Athanasius, the Synod of Hippo and the Council of Carthage. Additionally Didymus the blind wrote a commentary on all three epistles, showing the by the early 5th century they were being considered as a single unit.
The late attestation for 3 John in the 3rd century, and doubts about authority continuing until even later, is probably due to the lack of certainty regarding the epistles authorship. 1 John does not give direct information about its author, but it was considered apostolic, alongside the Gospel of John. " and 3 John, in comparison, are written by the mysterious "elder" or "Presbyter". This difference was responsible for the belief that 2 and 3 John were written by some one other than the apostle. Paradoxically their acceptance in to the canon was due to the change in belief that they were in fact of apostolic origin. However Brooke does caution that the late attestation may be due to the very short nature of the letter.