J.R.R. Tolkien is one of my favourite theologians. I wouldn't imagine that he would appear in many people's lists of favourite theolgians (I assume that other people keep such lists). For starters, his stories have 'gods' in them, and don't mention Christianity at all. In fact, this was a conscious choice for Tolkien. "Myth and fairy-story must, as all art, reflect and contain in solution elements of moral and religious truth (or error)", he once wrote, "but not explicit, not in the known form of the primary 'real' world." In fact, he felt that for myth to contain or reference Christianity explicitly was "fatal" for the story. In the form of myth, art could never capture Christian themes if it set out to reference explicitly the Christian story. That makes Tolkien a subtle theologian, but I love him for three main themes which he teaches me to feel, rather perhaps than to think, through his stories.
Firstly, Tolkien teaches me to feel the doctrine of creation. The creation myth from the Silmarillion is, to my mind, absolutely beautiful and to a very great degree truth-full. (I would say absolutely truth-full, but Tolkien's Roman Catholicism does peek through a bit in the role he assigns to his 'subordinate gods', the Valar - God is never quite so close to his creation as you feel he is in Scripture). I can't really describe it, except to say that portraying creation not as one act, but as the whole of history, and not as a fiat but as a composition, touches my heart with the wonder of God's creative act more than any other text I've come across. Tolkien really loved stuff - the stuff God has made (he had a much more ambiguous relationship with the sub-creativity of humanity). He makes me want to love stuff too, for the sake of its Creator.
Secondly, Tolkien helps me to feel the doctrine of the Fall. The Silmarillion is full of futility, and that same futility haunts the Lord of the Rings. We need heroes, but whenever we have had them they have been broken. Feanor is the greatest of the Noldor, but he dooms his people to exile and his family to destruction. Turin is noble, but ultimately is doomed by his own evil. Numenor is great, but is pulled down by its own pride, as will be in time its daughter realms in Arnor and Gonder. (As an aside, Tolkien's portrait of evil is profound - it is about wanting mastery, and in pursuit of mastery actually making yourself a vulnerable slave. Sauron seeks mastery through the ring; but by investing his energy in it, he makes himself vulnerable in ways he would never have been otherwise). An intervention is needed - at the end of the Silmarillion this is the Valar riding to war; in the Lord of the Rings, it doesn't really come, except in the sense of my third point below. In both cases, Tolkien understands that brokeness is brokeness, and evil is evil - even when both are redeemed for good. In the creation myth again, the theme of Melkor - the embodiment of evil - is woven into Iluvatar's (God's) overall purpose, but it is still ruinous. And Iluvatar's counter-theme is "deep and wide and beautiful, but slow and blended with an immeasurable sorrow, from which its beauty chiefly came". That seems to me to be the way the gospel deals with evil.
Thirdly, Tolkien gives me a picture of providence. Throughout the Lord of the Rings, the 'goodies' are preserved and at crucial moments very definitely helped by an outside force (think Frodo in the tunnel, chanting the name of Elbereth). The theme is shown profoundly in the two characters of Frodo and Gollum. Frodo wishes the ring had never come to him - "Why was I chosen?" Gandalf can only reply that he "may be sure that it was not for any merit that others do not possess". In fact, "Bilbo was meant to find the ring, and not by its maker. In which case you also were meant to have it, And that may be an encouraging thought." Frodo represents providence working itself out in the light. Gollum represents providence working itself out in shadow. He has just as much of a role to play as Frodo. Without him, the ring would not be destroyed. But he is the unwilling tool of providence. He is in some ways the Judas Iscariot of the book. And all of this relates back to the music at the beginning of the Silmarillion - which encompasses all themes, even those which rebel against the Chief Composer.
Okay, I admit it, I am a Tolkien fanboy. Now to get back to my 17th or 18th read through the Lord of the Rings (I lost count somewhere along the line)...