From Silmarillion:
Even as the first shadows were felt in Mirkwood there appeared in the west of Middle-earth the Istari, whom Men called the Wizards. None knew at that time whence they were, save C§ßrdan of the Havens, and only to Elrond and to Galadriel did he reveal that they came over the Sea. But afterwards it was said among the Elves that they were messengers sent by the Lords of the West to contest the power of Sauron, if he should arise again, and to move Elves and Men and all living things of good will to valiant deeds. In the likeness of Men they appeared, old but vigorous, and they changed little with the years, and aged but slowly, though great cares lay on them; great wisdom they had, and many powers of mind and hand. Long they journeyed far and wide among Elves and Men, and held converse also with beasts and with birds; and the peoples of Middle-earth gave to them many names, for their true names they did not reveal.
I am going to copy part of our discussion from FoTR that fits here... discussing Gandalf's ring, because I think it also fits, and I couldn't say it better:
I did manage to read the section on The Rings of Power from the Silmarillion last night, and one thing jumped out at me in particular. Gandalf's ring was the Ring of Fire. The name conjured up for me the image of his battle with the balrog in Moria, but that is not at all the emphasis presented in "The Rings of Power." Instead, the Ring of Fire which Gandalf possesses increases his ability to enflame the hearts of others to heroic deeds. Hence his ability to spark in the hobbits their drive and commitment to performing great acts of heroism beyond any that they themselves would beleive possible. I think about how each time one of them steps out, it is Gandalf who is present to spur them on--Frodo and Sam at the beginning, Merry and Pippin later on in the story. All who accept Gandalf's leadership arrive at greater achievements than they believe are even possible, all because of his encouragement and influence.
Just knowing that bit about the Ring of Fire really opened my eyes to Gandalf's role, particularly in how it worked itself out in his relationships with all the characters in the story.
"Take now this Ring," he [C¨ªrdan] said; "for thy labours and thy cares will be heavy, but in all it will support thee and defend thee from weariness. For this is the Ring of Fire, and herewith, maybe, thou shalt rekindle hearts to the valour of old in a world that grows chill."-Penny1
From that I read that Gandalf's role is to inspire the hearts of people to valor, his power is subtle, a mentoring that leads the hero to his own decision.
I like that better than "type of Christ". When I first began reading LotR, I felt there was something- Christ related with Gandalf, but not exactly a representation of Him, as I went on, and he would show up to encourage, inform or suggest after a course of action has begun or was getting bogged down, that kind of made me think he was more like the fundtion the Holy Spirit in my life.
It did occur to me that it might be similar to one of the Archangels- whereas only Lucifer fell to become Satan taking some angels with him- comp: Sauron/Sarumon's rebellion and the Orcs (corrupted Elves)
The other two Michael and Gabriel remained loyal.
I think you are right, that this is NOT an allegory, but it is interesting that he uses so many Christian tenets, and illustrations-
RE: Fire, Tolkien sure does use it in a lot of ways. Don't forget the the fire of the forge, both dwarf and elven- to strengthen and sharpen- The Balrog- to burn out impurities? remeber that Gwaihir said that Gandalf was light as a feather- and that the sun could see through him after his experience with the Balrog's fire. "I was burnt."
Sorry, I need a nap, getting rambling here.