elder. The writer obviously is the Apostle John, presumably writing from Ephesus to a close friend in one of the nearby churches of Asia Minor. Compare the salutation in yTerm 1.

wellbeloved. Gaius is called “beloved” by John no less than four times in this short epistle (zTerm 1, 2, 5, 11). He had evidently been won to Christ by John (zTerm 4), and John had frequently received good reports from traveling Bible teachers and others concerning his spiritual growth and godly life (zTerm 3).

in health. An expression of concern for the health and prosperity of the recipients was common in the pagan letters of the ancient Graeco/Roman world. John, however, added an expression of interest in their spiritual health as well.

walkest in the truth. See note on yTerm 4.

walk in truth. We should not only “know the truth” (John 8:32) and “believe and know the truth” (1 Timothy 4:3), but also obey the truth (1 Peter 1:22), speak the truth (Ephesians 4:15), do the truth (John 3:21) and, like Gaius, “walk in truth” (zTerm 4).

taking nothing. The traveling evangelists and Bible teachers recommended by John to the various churches were evidently called of God to such a ministry, depending on God and God's people to supply their physical needs. They set a good example for modern preachers, too many of whom plead for money from saved and unsaved alike, thereby giving the cause of Christ a bad name. To maintain the integrity of His Name (meaning all He is and all He represents), Christian leaders today likewise should trust God and His people alone to supply their needs.

receive such. John says that other Christians in the churches should “receive” these dedicated servants of the Lord. The word “receive,” as used here, conveys the thought of “underwriting,” or supporting them physically and financially.

church. John apparently had written a previous letter to this church, but Diotrephes somehow intercepted it and refused to honor John's request to help and hear the itinerant Bible teachers, even going so far as to excommunicate those who disagreed with him (zTerm 10).

Diotrephes. “Diotrephes” means “Nourished by Zeus,” and Diotrephes had chosen to keep his pagan name rather than to follow the custom of other Gentile converts and change it to a Christian name. He was evidently only half-converted from paganism, and resisted any teaching from John or other God-called teachers. Nevertheless, he had somehow gotten himself elevated by the congregation to the highest position of power in the church, able even to ignore or reject even the teachings of the Apostle John himself. He loved his position of power and was intent on keeping it. John was hoping he might soon be able to come and deal with the situation personally (zTerm 10), though his health and age might not allow (but note zTerm 13 and 14).

doeth good. People sometimes make fun of those they call “do-gooders,” but God's Word honors them. God Himself “did good” (Acts 14:17) in creating our world and us, and Jesus “went about doing good” when He was on earth (Acts 10:38). He commands us to “do good unto all men, especially unto them who are of the household of faith” (Galatians 6:10), and even to “do good to them which hate you” (Luke 6:27). As this verse affirms, “he that doeth good is of God.”

Demetrius. Demetrius is probably not the same Demetrius encountered some thirty years before by Paul at Ephesus (Acts 19:24, 38), although it is conceivable that the Ephesian silversmith could have been converted later through the church that had been established and become strong there despite his opposition. In any case, the Demetrius mentioned here was well-known to John, who was now at Ephesus, and was probably being entrusted with carrying this letter from Ephesus to Gaius and the church where Gaius served.