If you are a J R R Tolkien fan, you owe it to yourself to pick up one of the several excellent Tolkien & “Inklings” reference books by my friend Colin Duriez. Colin has great insight into Tolkien, Lewis, et al. Here I’m posting his essay “Christianity, Tolkien and,” from the wonderful J. R. R. Tolkien Handbook (Baker, 1992) (the following uses my typical abbreviations; “xn” is Christian, “xnty” Christianity, “T” is Tolkien):
[If this topic interests you, may I also recommend the issue of Christian History & Biography I edited on Tolkien. It's available here. You can also browse previews of the issue's articles here. For Duriez's equally fine essay on the "theology of story" implicit in the work of C S Lewis, J R R Tolkien, and Charles Williams, see here.]
Christianity, Tolkien and
“According to Paul H. Kocher, T was inspired and guided on his way by the mythology of Denmark, Germany, Norway and especially Iceland (see MYTH; IMAGINATION). The Norse pantheon of gods was headed by Odin. This is particularly clear as embodied in the Icelandic Elder Edda and Younger Edda, and the Icelandic sagas. As a Christian, T rejected much of the Norse world outlook, but admired its imaginative power. Those elements that he could transform into xn meaning, he kept. Of course, he rejected the idea of a polytheistic assembly of gods. Also, he rejected its concept of fate, which conditioned not only mankind, but the gods. Instead, he attempted to portray a biblical vision of providence.* This was a central theme of his fiction. Equally central was a passionate portrayal of freewill, which also rejected fate. 
“Although Norse-Icelandic mythology has a void or chaos at the beginning of creation, this is not the biblical creation out of nothing, ex nihilo, to which T was committed. So there is a sharp distinction here between T’s invented mythology and that of the old Norse peoples.
“Paul Kocher points out that T also rejected the Norse idea of the ending of the world in the Twilight of the gods (Ragnarok). Yet, imaginatively, he retains the northern atmosphere of heroic endurance, as in the Elves enduring the Doom of Mandos,* or in the stoicism of the great army of the West advancing to the gates of Mordor. T has, in place of the Twilight of the gods, suggestions of a Last Battle at the end of the ages after the Fourth Age* of Middle-earth* that is full of the Christian hope of the end of the world.
“T sets The Silmarillion* in a pre-Christian age (like the author of Beowulf) so it can’t express the full hope of xnty, only prefigure it. According to Kocher, its theme is ‘Morgoth’s implanting of the seeds of evil in the hearts of Elves and Men, which will bear evil fruit until the last days’. In this outworking of the theme of evil,* Sauron* plays a crucial role in the first Three Ages of the world of Middle-earth.*
“An important element in the embodiment of xn meaning in T’s fiction comes from his theory of sub-creation.* The Silmarillion, The Lord of the Rings* and even The Hobbit* are attempts at sub-creation, and as such try to ‘survey the depths of space and time’. T is particularly concerned with time, and Christian apocalyptic.* That is, his theme is to reveal the essential meaning behind human history. Pre-eminently like the biblical Book of Revelation, he is concerned to bring hope and consolation in dark and difficult days.
To appreciate the freshness and depth of Christian  meaning in T’s work, he can be compared with John Milton, the author of the epic poem, Paradise Lost. It could be argued that the legacy of Milton’s work is with us still, in science fiction and fantasy. There are important parallels between T’s fiction and Milton’s great work—both are a study of evil,* and a defence of God’s ways to mankind. In T, Morgoth* and his servant Sauron* are of central importance, as Satan is in Paradise Lost. The very title of T’s popular trilogy refers to Sauron, the dark Lord of the Rings. As also in Milton’s work, the theme of fall from grace (disgrace) and into sin or chosen wickedness predominates.
“Clyde S. Kilby was able to spend much of the summer of 1966 working with T on the unfinished The Silmarillion, and asked him many questions concerning the underlying meanings of his work. In his little book, Tolkien and The Silmarillion, he discusses T as a Christian writer. Kilby describes him as a Tridentine Roman Catholic [that is, someone committed to the Roman Catholic distinctives hammered out at the 16th-century Council of Trent], a convinced supernaturalist. He believed in a personal yet infinte God who could answer prayer. He and his wife believed that one of their sons had been healed of a heart complaint. Talking to T had been a major factor in the conversion of C. S. Lewis to Christianity. T had a high view of Mary the mother of Jesus. His own faith was tied up with that of his mother, who had been ostracized for her faith. He believed that this was a factor in her death. He lost her before his teens. Kilby also mentions T’s work on The Jerusalem Bible.
“Although the name of God doesn’t appear in T’s fiction (there he is called Iluvatar*), it is full of xn meaning. T spoke to Clyde Kilby, for instance of the invocations to Elbereth Gilthoniel. The Professor characteristically wrote in The Road Goes Ever On: ‘These and other references to religion in The Lord of the Rings are frequently overlooked.’ The meaning, in fact, is implicit  rather than explicit. It is incarnate in the whole world of the story. T deliberately avoided cultic or other explicit references to religion. His interest was in theology, philosophy and cosmology—the elements which make xnty a world outlook rather than merely a matter of private and public religious experience. It was part of T’s view of mankind as sub-creator, in God’s image, that human sub-creations would be like all possible worlds created by God in having a moral and religious character or ‘nature’.*
“Before and since T’s death there have been numerous articles and books on the meaning of his fiction. Kilby records T’s favourable reaction to an essay sent him from Australia, concerned with the themes of kingship, priesthood and prophecy in The Lord of the Rings. He endorsed the spirit of the essay in finding xn meaning in his work, even though, as he remarked, it displayed the tendency of such scholarly analysis to suggest that it was a conscious schema for him as he wrote. He didn’t deliberately try to insert xn meaning into his work—a point over which he disagreed with C. S. Lewis, in whose fantasy he felt the xnty was too explicit.
“A fruitful way of considering xn meaning in T is in terms of his commitment to a natural theology.* C. S. Lewis, in his book, Miracles, emphasized the importance of presuppositions or our preunderstanding in approaching historical and natural events. T, on the contrary, finds real history and natural events a reliable guide to truth in themselves. Whereas traditional natural theology concentrates on the revelation of God in nature and cosmology, T particularly finds inevitable theology revealed in language and story, or myth.*
Clyde Kilby points out that T believed in the anima naturaliter christiana, ‘the sense of God and responsibility to Him inborn in mankind’. This sense is both reflected in language and story and reinforced by them. 
“T’s thinking about this inevitable structure of the language of story is most clearly found in his essay, ‘On Fairy-Stories’.* Here he finds the attributes of escape,* recovery* and consolation.* Consolation, particularly, is loaded with xn meaning, focused on the evangelium. This structure of story is vindicated by the greatest story of all, told in the biblical gospels. This has the story qualities of escape, recovery and consolation, yet is, astoundingly, true in the real world, in actual human history.
[I break in here: is it possible that T “reasoned to the faith” from story and the imagination? It seems this was the gist of his talk with CSL on Addison’s Walk! And perhaps this priority of story—or at least of language and words and their power—is rooted in Barfield’s Poetic Diction. See Duriez’s entry on natural theology for more on this. Maybe this is where I can use Tolkien as a “wedge” into Medieval Wisdom: he saw the way not just the created order but History itself was charged with theological meaning. This relates to my several themes of (1) sacramentalism (holistic anthropology and the sense of God in all creation), (2) memory (its vital necessity for any community—not least the Christian community—to hold together and sustain itself), and (3) intertextuality (as CSL points out in Discarded Image, this is the Medieval Trait par excellence—this veneration for old texts; locating of meaning itself in the authority of old texts), all interwoven.]
“The inspiration for T’s fiction came from such xn works of medieval English literature as Beowulf and Crist. One sentence in the latter in particular inspired the tale of Earendil* the mariner. The line was Eala Earendel engla beorhtast ofer middengeard monnum sended. Commenting on this sentence in a letter to Clyde Kilby, T declared that these are ‘Cynewulf’s words from which ultimately sprang the whole of my mythology’. T gave a literal translation of the line to Kilby: ‘Here Earendel, brightest of angels, sent from God to men.’ [see Duriez’s entry on angels—there are many angel-figures in T’s mythos]
“As well as his natural theology, T was deeply inspired by, or at least found himself using parallels with, biblical imagery. Kilby is useful in pointing out some of these biblical associations. A study of them would take a whole book. These associations include biblical imagery of trees,* the fall* of mankind and some angels, the personification of Wisdom in Proverbs 8, and the biblical portrayal of heroism (see HERO).
“In a letter to W. H. Auden* (in 1965), T commented on The Lord of the Rings in relation to Christian theology: ‘I don’t feel under any obligation to make my story fit with formalized Christian theology, though I actually intended it to be consonant with Christian thought and belief.’