Hmmm, does your brother consider Catholics demonic too?
If not, then you might want to point out to him that Tolkien was a deeply faithful Catholic, and his faith comes out in several places in the trilogy. Quite a few articles came out about it in the weeks after Return of the King debuted.
Qwinn
Trust me, I have debated this point with him till I'm blue in the face. We have never been close, he never read and he doesn't trust me much. He didn't realize FOTR would scare his younger children and saw Nazgul as demons, wizardry and scorcery etc. He just needs to read the books in order to understand.... if he ever would.