"Heathen" was used as an insult by Christians for anyone with the wrong faith originally. I don't remember if Lutherans called Catholics heathens or the other way around. It was also used for anyone who wasn't Christian. So I guess it fits for every middle-european faith.
oh my goodness, okay everyone it’s okay ‘cause I have used the magic of google to venture forth and hunt us all some wisdom, so now I bequeath unto you all the epic bounty that is;
and a 15-page paper by a graduate student at the University of Iceland for anyone who either wants to register or whatever with academia.edu or, if you can’t be arsed with that, just wants me to send them the file 🙂
(spoiler though, it is for all Germanic paganism in general)