Íluvatar's opponents?

[Aratlithiel]

This brings me back to my intial view that, having created beings with free will, it was up to those beings to determine the fate of Arda. In that sense, it might be said that Eru has no opponents because he is not "playing the game". He set it in motion, but then stood back and let the beings he created battle it out.

I like that - very succint. I need to take composition lessons from Saucepan Man.