This means that the servants of God have accepted no assistance from those who are not believers.
Source: INTRODUCTORY COMMENTARY ON 3 JOHN
3 John 1:7
7 Because that for his name's sake they went forth, taking nothing of the Gentiles.
Commentaries
For they went out for the sake of the name, accepting nothing from the Gentiles. When it says for the name, it is to be understood as of the Lord Jesus Christ. For the ancients spoke in this manner. And for two reasons, they went out for the name of the Lord, either to preach, evidently coming of their own accord in the name of Him, or because of the faith and confession of the holy name, they were expelled from their homeland by their fellow citizens or relatives.