There is no good reason to assume that idolatry is limited to non Jews. There are plenty of Jews which worship dead people- and hang their portraits all over the place. We know that to marry a worshiper of idols is forbidden, but that does not mean a gentile. Rather all religious Jews worship dead people. \[The fact of their worship of dead people does not help them to be considered Jewish even though they might make a show and dance of their adherence to rituals. The religious Jews that worship the pictures of dead people shows they are idolaters. [In fact the overly strict adherence חומרות יתירות to rituals might be thought to hide an intension to pretend to be kosher, while in fact hiding some hidden agenda to entice others to their worship of dead people. []
