John writes this letter to encourage some fellow believers. He writes to Gaius and testifies to his great hospitality, which he praises. He says that someone who does such good is from God. He goes on to tell him to expel Diotrephes, who has not learned to do the same thing. He also praises Demetrius for doing the same as Gaius and mentions his faith as a testimony to his virtue. His main purpose for writing is the same as it was in his second letter.

Who this Gaius was and what he was like becomes apparent in the course of the letter. He was a man who had believed in Christ and as a result of that was living a life of good works. He was not a preacher himself, but he was happy to support the preaching ministry out of his own pocket. He is probably to be identified with the Gaius mentioned by Paul as his host.^[1] For Gaius was a host to the whole church, who opened his doors to everyone who came along, whether they were the preachers or the hearers of the Word.

The person who loves God with heartfelt charity loves in the truth, a point which John often makes in his other letters.

Things are going well for Gaius because his soul is carrying on in good works as the will of his mind directs him.

It is John’s earnest desire and prayer that Gaius should go on to complete the good works which he intends to do. His heart is already in the right place, which is the necessary precondition for fulfilling the rest.

Gaius is doing well, says John, because he is living according to the truth of the gospel.

The truth of Gaius’s life was seen in the perfection of his works. He was a man who went about without any guile in thought, word or deed. Instead of that, he followed the commandments of God to the best of his ability.

Gaius is walking in the truth because he is following the gospel in all its pure simplicity. To walk does not mean to put one foot in front of the other but to make orderly spiritual progress within the limits of what the soul is able to bear. This is something which very few people manage to achieve.

There is no greater joy than to know that those who have heard the gospel are now putting it into practice by the way in which they live.

Gaius’s loyalty is the result of his faith. What John means is that Gaius is doing all these things because he is a believer and wants to show his faith in the things that he does.

Visitors praised Gaius to the rest of the church because of his generous hospitality to those who were in God’s service.

This means that the servants of God have accepted no assistance from those who are not believers.

There are two possible reasons why these people have set out for the sake of Christ. One is that they had gone of their own free will to preach the name of Christ. The other is that they had been expelled from their homes because of their faith in his holy name.

Whoever gives practical assistance to those who have spiritual gifts becomes a coworker with those people in their spiritual work. There are relatively few people who are spiritually gifted but many who are rich in the things of this world, and when the latter comfort poor saints with their wealth they gain a share in their spiritual riches.

John teaches us that we should not wait for such needy people to come to us but should rather go out and look for them, for that is what Lot and Abraham did.