Was the maniac of Gadara a Gentile?
The maniac of Gadara was not a Gentile. The context explains that the first three letters of Gadarene are Gad, identifying him as a descendant of the tribe of Gad, an Israelite tribe that settled east of the Jordan River. Jesus' only Gentile encounters were the Canaanite woman and the Roman centurion.
Les explains that in Christ's earthly ministry, Jesus had dealings with only two Gentiles: the Canaanite woman and the Roman centurion. When someone asks about the maniac in Gadara from whom Jesus cast out a legion of demons, Les insists he was not a Gentile. His stock answer is to ask what the first three letters of the word Gadarene are: Gad. Therefore, the maniac was a descendant of the tribe of Gad, which lived on the east side of the Jordan River. This connects to Joshua's settlement, where Reuben, Gad, and the half-tribe of Manasseh remained east of the Jordan.