[Formendacil]

My general take on the matter is that in the "physics" of Middle-earth, to use the word somewhat unorthodoxly, Tolkien went with a most Nordic look, feel, and air. He says as much himself, and a quick glance at the mythology he borrows from and his lifelong interests corroborate the story readily.

However, in the metaphysics of Middle-earth (here, however, I use the word somewhat more conventionally), I would say he hies closer to the Catholic side of things. This Catholicity doesn't come through very much in the externals (the "physics") of the stories, but I think it's there in what underlies them: in things like the Long Defeat/Eucatastrophe relationship, the goodness of Matter mixed with its corruption by the Prime Evil, and idea of a historically-grounded redemption.