In style, 2 and 3 John are very much alike, indicating that the sender of both letters is the person who identified himself as “the presbyter” or “the elder.” The ancient questioning regarding 3 John is the same as for 2 John, with doubts having been raised about whether the apostle John is the elder who wrote these two letters. In 3 John, like in 2 John, the writer does not identify himself as the apostle. For this reason, the commentary that follows will refer to him as the “elder.” (See the introduction for 2 John, as the comments of Eusebius and Origen apply also to 3 John.)
It is unlikely that this brief personal letter would have been extensively copied, recopied, and circulated. This may explain why it is not represented among the earliest extant papyrus manuscripts.
Third John praises Gaius for his exemplary love, commends Demetrius as a believer with an outstanding reputation, and exposes the wrong attitude and high-handed actions of Diotrephes who jealously tried to secure his position as the foremost one in the local congregation. Nothing in the letter makes it possible to identify where Gaius lived. Three of the apostle Paul’s close associates were named Gaius. One was a Macedonian, another Gaius came from Derbe in Asia Minor, and the third, one of the few believers whom Paul had personally baptized, resided in Corinth. (Acts 19:29; 20:4; Romans 16:23; 1 Corinthians 1:14) Nothing contained in 3 John identifies Gaius with any one of these three believers, and it is far more likely that he is yet another believer named Gaius.