A Bloody and Barbarous God investigates the relationship between gnosticism, a system of thought that argues that the cosmos is evil and that the human spirit must strive for liberation from manifest existence, and the perennial philosophy, a study of the highest common factor in all esoteric religions, and how these traditions have influenced the later novels of Cormac McCarthy, namely, Blood Meridian, All the Pretty Horses, The Crossing, Cities of the Plain, No Country for Old Men, and The Road. Mundik argues that McCarthy continually strives to evolve an explanatory theodicy throughout his work, and that his novels are, to a lesser or greater extent, concerned with the meaning of human existence in relation to the presence of evil and the nature of the divine.