Introduction to III John
As in his second epistle, John, rather than mentioning his name, introduces this letter as coming simply from “the elder.” III John is even more personal than II John, being addressed to an individual, “the wellbeloved Gaius” (III John 1), apparently a responsible leader in a church where John had formerly ministered (note the reference to “my children” in III John 4).
Presumably this epistle, in common with I John and II John, were written by the Apostle John from Ephesus some time around A.D. 90 (see the Introductions to I John and II John). His occasion for writing Gaius was to encourage him in handling a disagreement in the church between two men, Diotrephes and Demetrius. The former was trying to rule the church in a tyrannical fashion, and needed to be rebuked, whereas Demetrius was sincerely trying to implement John’s teachings. John himself was hoping soon to visit the church (III John 14), just as he was hoping to visit that of the “elect lady” of II John 12.
John places great emphasis on “the truth” in all three epistles. It is significant that he not only stresses teaching the truth, but also doing the truth (I John 1:6) and “walking in” the truth (II John 4; III John 3-4). He even notes that Demetrius had a “good report” of the truth (III John 12).
Note also the Introductions to John, I John, II John and Revelation, all of which were written by the same man, John the Apostle.