The Greek adjective “ἐθνικός”

Limited to Mt. 5:47; 6:7; 18:17; 3 Jn. 7, the Greek adjective “ethnikos” meant “heathen” or “Gentile.”  This noun is always plural in the New Testament and it describes Gentiles in contrast to Jews.  John (3 Jn. 7) spoke of Christians “taking nothing” (ASV) from the “Gentiles” (those outside the faith) when discussing missionary work.