Stephen King's Pet Sematary is often hailed as his most chilling and disturbing work, a sentiment that King himself appears to share. The novel is complex, weaving together a range of themes and social issues. At its heart, the narrative explores the innate human urge to challenge the natural order, particularly through the revival of the deceased. This age-old challenge of distinguishing between the divine and the mortal is introduced to the reader right from the start. To emphasize this contrast, King opens several sections of the book with New Testament passages about Jesus bringing Lazarus back to life.

Furthermore, by portraying the main character as a scientist — specifically, a medical doctor — King reflects a Promethean perspective on the quest for scientific knowledge, a theme that has been prevalent in literature since Mary Shelley's time.

On another thematic level, King revisits the idea of the "Bad Place," which he explored in The Shining (1977) and other works. In this story, it is the ancient burial ground of the nearly extinct Micmac Indians, a location filled with cultural myths and dread. This site, with its long-dormant malevolent power, is reawakening. Additionally, as often seen in King's exploration of these themes, there's an assertion that evil can only fulfill its objectives by controlling and eventually absorbing human beings. The novel is permeated with a sense of helplessness, and arguably, except for Cujo, it stands as King's most pessimistic commentary on the human condition.

While the novel is primarily grounded in a naturalistic setting, there is an underlying theme that is only subtly suggested in The Shining — the idea of moral accountability for one's actions. Throughout the story, a mysterious phrase repeatedly appears at pivotal moments: "A man grows what he can... and tends it." Both the reader and the main character, Louis Creed, slowly come to understand and value its deeper metaphorical meaning. This focus on the inevitable outcomes of moral responsibility, a significant aspect in King's later works, might be the key to comprehending and accepting an ending that some readers find too terrifying to even contemplate.