LOTR has many Christian themes even though it doesn't parallel the Bible. The story itself is centered around a struggle between the forces of good and evil, with human beings portrayed as a morally weak and lethargic group. In the end, the forces of good are saved from total destruction by the act of a single person. Frodo is most definitely a Christ figure: he is chosen for the task of disposing of the ring, most people doubted his ability to do it, and he sacrifices a lot to complete his mission. Aragorn is probably like one of the Apostles, like John, because he knows he can't be or do what Frodo does, but is forever loyal to Frodo and the cause.