John Gill Commentary 3 John 1:8

"We therefore ought to welcome such, that we may be fellow-workers for the truth." — 3 John 1:8 (ASV)

We therefore ought to receive such We who are Jews, who have believed in Christ, ought therefore 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; for such a one as Gaius, it seems, as well as the apostle, were such.

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. 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".