Why did the missionaries not accept financial assistance from the Gentiles?
3 John 5-8 (NASB)
5 Beloved, you are acting faithfully in whatever you accomplish for
the brothers and sisters, and [a]especially when they are strangers; 6
and they have testified to your love before the church. You will do
well to [b]send them on their way in a manner worthy of God. 7 For
they went out for the sake of the Name, accepting nothing from the
Gentiles. 8 Therefore we ought to [c]support such people, so that we
may [d]prove to be fellow workers [e]with the truth.
The traveling Christian preachers were ", accepting nothing from the Gentiles" -people of the nations. He obviously wanted the travelling preachers to preach the gospel, without financial burden to the gentiles, whom they were preaching.
1 Corinthians 9:18 (NASB)
18 What, then, is my reward? That, when I preach the gospel, I may
offer the gospel without charge, so as not to make full use of my
right in the gospel..
2 Corinthians 11:7 (NASB)
7 Or did I commit a sin by humbling myself so that you might be
exalted because I preached the gospel of God to you without charge?
1 Thessalonians 2:9 (NASB)
9 For you recall, brothers and sisters, our labor and hardship: it was
by working night and day so as not to be a burden to any of you, that
we proclaimed to you the gospel of God
At the same time, Paul urges his fellow Christians to help such traveling preachers, "Vs 8 reads "Therefore we ought to support such people, so that we may prove to be fellow workers with the truth." By doing so, they were assisting in furthering the interests of Christianity, thus they proved to be "fellow workers in the truth.