The Kelevala, a Finnish mythos, is where the whole middle earth scenario comes from, and helps explain why the ME languages resemble Finnish. Tolkien was a linguist, after all.
In fact, the name Gandalf comes from the Icelandic Voluspa, and the Elder and Younger Edda contain the forest of Myrkwood, as well as the Dwarven kingdoms. Still Pagan mythology. The name, however, is also a Norwegian King's name in The Heimskringla.
Tolkien was also enamored of Beowulf, by his own admission (he was considered a leading authority on Old English). And Welsh was another specialty of his, The Mabinogion being an influence on his Red Book of Westmarch (Sustitute the Red book of Hergest...).
I won't deny your analysis of "power divorced from authority", but from a purely Christian standpoint, the fatalism of Nordic and Celtic Mythology is more akin to Islam ("It is Allah's will that we suffer") than to Christianity ("God gives one a choice, it is up to us to take responsibility").