I. John receives a good report of Gaius's faith and charity from the brethren. Gaius’s love for the brethren and hospitality to strangers proves his sincerity in the faith. II. Gaius is commended for his hospitality, a virtue extended to strangers and those of different churches. III. John expresses great joy in hearing of Gaius's walk in truth. This reflects the joy of ministers when they see their followers living out their faith. IV. John advises Gaius to continue supporting the brethren by aiding them on their journeys in a godly manner, reflecting Christian generosity. V. The brethren went forth preaching for God's sake, taking nothing from the Gentiles. John emphasizes the need for the church to support such ministers, as they help propagate the truth.

We therefore ought to receive such - Those who are persecuted for righteousness' sake, and have professed the truth at the hazard of their lives, and the loss of all their worldly substance. Instead of απολαμβανειν, to receive, the most ancient and reputable MSS. have ὑπολαμβανειν, to take up, undertake for, or kindly receive.
Fellow helpers to the truth - And thus encourage the persecuted, and contribute to the spread and maintenance of the Gospel.

We therefore ought to receive such,.... We who are Jews, that have believed in Christ, for such an one Gaius, it seems, as well, as the apostle, were, ought to receive such preachers of the word into our houses, and entertain them cheerfully, while they continue, and supply them with all necessaries when they depart:

that we might be fellow helpers to the truth; that is, to the Gospel, and the propagation of it in the world: some are helpers to it, in preaching of it, by making use of the ministerial gifts bestowed upon them; and others are fellow helpers with them, to the same good work, by their purses, communicating freely to the support of those, who labour in the word and doctrine; and these latter have the honour to be co-workers, or fellow labourers with the former, as the word here used signifies. The Alexandrian copy reads, "fellow helpers to the church", that so the whole burden of taking care of these ministers might not lie upon them. The Vulgate Latin, Arabic, and Ethiopic versions read, "fellow helpers of the truth".

We--in contradistinction to "the Gentiles" or "heathen" referred to, Jo3 1:7.

therefore--as they take nothing from the Gentiles or heathen.

receive--The oldest manuscripts read, "take up." As they "take" nothing from the Gentiles, we ought to take them up so as to support them.

fellow helpers--with them.

to the truth--that is, to promote the truth.