Most Fundamentalist Christians in my experience (and I do have some experience with them, having argued with many and dated a few) boil Christianity as a whole to a few basic precepts. The most important is that Jesus of Nazareth was the begotten son of God, born to the (at the time) Virgin Mary, and that Jesus is the Savior of all mankind, having given Himself in sacrifice at the Cross. This is the central tenet pervading most fundamentalist sects.
But, see, fundamentalism is also NOT an organized religion, strictly. Citing Biblical passages, fundamentalists do not have a unifying structure that co-ordinates their theology. Each fundamentalist Church--as in the pastor, building, and congregation--is its own Christ-worshiping entity, not governed by a greater (mundane) hierarchy. To most fundamentalists, Christianity is the name for the belief that Christ is Savior and that Faith in Him is the path to Salvation. So yeah, they aren't going to believe that Christianity is a living thing, because Christianity is only a word that is shorthand for a single belief.
