Now that we’ve gotten far afield, I’ll say the reason the Exorcist wasn’t particularly scary to me is that I’m more afraid of what humans are capable of doing to other humans - the supernatural doesn’t hold much suspense for me.
I know it was used famously in The Exorcist, but I keep thinking I remember a very old sci-fi movie where the alien cries “It burns! It burns!” as it disintigrates?
Was the alien a zombie?