One of the main themes of the poems is religion or Christianity. Hughes wrote his piece as a critical commentary on Christianity and the teachings about God and his greatest creation—humans, or, as Hughes says, Men. God’s power is slightly demoted when He encounters the nightmare. While considered the Almighty in Christianity, God is depicted as an entity that experiences fear. Crow, in this case, becomes God's companion who attempts to improve God's Creation. At the same time, Crow is on a search for his own female Creator. The crow both works with and challenges God; it oftentimes has an agenda of its own beyond God’s plan. Another common concept that Hughes incorporates is gender and sexuality, particularly how these ideas are treated in Christianity. The crow flips ideas of creation and sex, even suggesting crudely that he shaped the male and female genitalia by snapping a worm in two. This near-vulgar description in an episode of the poem challenges the norms of Christianity.

Hughes takes inspiration from folklore and mythology, more specifically from stories about the popular mythological character known as the trickster. This creature, be it a god, a goddess, a human, an animal, or even a spirit, plays the role of both creator and destroyer and hero and anti-hero, as he/she/they/it unapologetically uses his/her/their/its power, wisdom, knowledge, and intellect to play tricks on people and disrupt God's work and the natural flow of events. Hughes used mythology to explain death, rebirth, life, and human nature and its complexity. The poetry anthology itself was designed to be an epic folktale that explores the beginning and end of life in the universe itself. The crow, as the role of the trickster, therefore has the opportunity to reflect upon the morality of his (and humanity’s) actions. There is an understanding that we—and the crow—are part of a larger, overarching narrative. There are histories embedded in everything we do; some day, these stories will be only distant memories. 

Throughout the work, Hughes incorporates the theme of nature, its energy, and humans' connection to it. He masterfully connects this to the ultimate spiritual awakening and development of all people and alludes back to the poetic spiritual journey through life. In “Crow Tyrannosaurus,” the crow is likened to the prehistoric Tyrannosaurus Rex. The crow notes that both he and the Rex are bound to the same laws that all creatures are: in order to survive, they must kill. Part of the crow’s existence—and presumably, humanity’s—requires participation in an element of destruction. This “natural order” is championed in the sense that it cannot be denied. Even if the crow wishes to change or break from the cycle of “kill or be killed,” he is ultimately bound by his natural design. He is compelled to kill or destroy despite contemplating the ethics of this behavior. Humanity and the creatures that God has created are also confined to the natural world’s strict confines. It becomes an eternal struggle of wanting to do or be more, yet being physically unable to transcend nature.