Despite an undeviating opinion on the subject, his greatest work The Lord of the Rings, is replete with free-floating allegory to Christian characters. Characters and situations that suggest Biblical situations, both narratively and on the level of spirituality and ethics. Each character within biblical text correlates with one or more characters in Tolkien’s work, thus free floating. Tolkien is a devoutly religious author who processes the world, including his own fantasies, through the lens of his faith. While Tolkien draws from different elements of theology in several different ways—such as interchanging his characters to represent various aspects of key Biblical figures—it is clear that Tolkien assigned a moral, free-flowing, yet religious allegorical backbone to his work.
Koch, Alexander B., "The Catholic Core of a Celebrated Composition" (2017). 4610 English: Individual Authors: J.R.R. Tolkien. 18.