Third Epistle of John in Smiths Bible Dictionary

The third epistle is addressed to Caius or Gaius. He was probably a convert of St. John, Epist. 3Jo 1:4 and a layman of wealth and distinction, Epits. 3Jo 1:5 in some city near Ephesus. The object of St. John in writing the second epistle was to warn the lady to whom he wrote against abetting the teaching known as that of Basilides and his followers, by perhaps an undue kindness displayed by her toward the preachers of the false doctrine. The third epistle was written for the purpose of commending to the kindness and hospitality of Caius some Christians who were strangers in the place where he lived. It is probably that these Christians carried this letter with them to Caius as their introduction.