I think we can detect some influences in the notion of the flame being eternal, of the maiar serving the flame, etc. No question, Catholicism (English Catholicism) is the greatest influence on Tolkien -- but not the only one, as you mention the Norse myths, Beowulf etc. And yeah, he had defend himself against other Catholics who worried his books weren't Catholic enough (what is he trying to say with Tom Bombadil . . .)
But the Greek Chaos -- Moorcock does use chaos that way. Remember in Stormbringer when the chaos stuff was seeping into the world and changing people's bodies to half human / half white worm and such? It's the primordial void and entropy as well, because it obeys no laws it can contain all contradictions and give rise to all potential resolutions. Gygax ripped this off -- the Githzeri impose law on chaos and build monasteries in Limbo. You're right on about the Greek view of the world but can't agree that didn't have an impact on Moorcock -- remember Elric destroys the world to usher in a new one. The swirling chaos at the end of the Saga is the necessary prerequisite for the creation of the new order to come. It's primordial soup. And, in the new order, Stormbringer is no longer an a pure agent of chaos but also an exemplar of the new concept of evil . . .
