The inescapable sin of human nature
Lester’s actions mark him as a deranged necrophile and serial killer, but the way he is depicted also marks him as human. Calling him “a child of God much like yourself perhaps” (4) draws parallels between Lester and the average person, and invokes empathy in the reader. His character could potentially be any man. His heinous acts come to represent the sins of all of ‘God’s children,’ and the inevitability of his downfall into murder represents the inevitability of human sin. All humans will fall to some sort of sin, as Lester fell to his depravity.
Because of the tone of the novel, bleak but starkly realistic, it takes the form of an account of human desire instead of a gruesome tale of a monster. Lester does not become a monster, instead his repressed desires are only revealed as the story progresses. This shows that his sinful nature is an element of all humankind, though it is often hidden.
The individual against society
Lester’s story begins with his fight against the county and the auctioneer to save his childhood home, which results in him getting cast out. Lester continues to only associate with society when it is necessary, and these interactions result in conflict nearly every time. Eventually, his indiscretions conflict with the community enough that the sheriff tells him "you are either going to have to find some other way to live or some other place in the world to do it in" (123). Lester cannot fit his nature and desires into the societal standards, so he rejects society and retreats into the cave.
The inherent beauty of nature
McCarthy describes nature with awe and longing, even when describing the gruesomeness of death. When depicting a pack of hunting dogs killing a boar, it says that “Ballard watched this ballet tilt and swirl and churn mud up through the snow and watched the lovely blood welter there in its holograph of battle, spray burst from a ruptured lung, the dark heart's blood, pinwheel and pirouette, until shots rang and all was done" (69). The words “ballet” and “lovely” make this scene beautiful, despite the ugly event that is happening. Because of how this is being described, it shows the inherent beauty and purity of nature. This same technique is used throughout the book, most notably when describing the cave and corpses within it. This shows that even death has its own sense of beauty because it is a part of nature.