[Mithalwen]

I think that Tolkien did see the Istari being Maia as angelic beings, and they are incarnate, but Gandalf makes it clear that he is a messenger and servant of a greater power so the Jesus comparison is perhaps too strong though I am not much of a theologian (there are some around though so you may get a more erudite answer). Saruman could be seen as a Fallen Angel like Satan in Paradise lost. I would contest that evil is so black and white in the Silmarillion. Morgoth yes but there are plenty of his adversaries who are not whiter than white.