While Monkey has several themes, the most significant one is that of Buddhist enlightenment. Buddhist principles pervade the story, with each main character representing aspects of human existence that are either desirable or less desirable, and each adventure highlighting different aspects of Buddhist teaching. Tripitaka and Monkey, the two pilgrims who become Buddhas, represent the qualities best prized in Buddhism—Tripitaka for his piety, humility, and understanding of how to treat others, and Monkey for his brilliance and great skill in life. Both are also vegetarians, which is common in Buddhism. Though they represent the best qualities, both Monkey and Tripitaka have flaws. Their ability to overcome their flaws and learn how to be better makes them worthy of promotion in the Faith—Monkey for conquering his ego and Tripitaka for conquering his fragility. By contrast, Pigsy’s attachment to earthly pleasures, his laziness, and his poor attitude make him unworthy of Buddhahood despite his contributions to the journey.

Karma and reincarnation play an enormous role in the text. Many of the creatures in the story turned out the way they are through some karmic accident or through committing a sin so great that it influenced their next reincarnation.