Demonology by King James I of England, first published in 1597, is a seminal work reflecting the fears, beliefs, and religious anxieties of late sixteenth-century Europe. Written in the form of a philosophical dialogue, the book presents King James’s firm conviction in the real and dangerous presence of witches, demons, and supernatural forces actively at work in the world. Divided into three books, Demonology explores witchcraft, necromancy, possession, and the nature of evil spirits. King James draws heavily on theology, classical sources, and contemporary accounts to argue that witches enter into literal pacts with the Devil and possess genuine supernatural powers. He strongly rejects skeptical views—such as those advanced by Reginald Scot—and insists that disbelief in witchcraft undermines Christian faith and divine authority. The work is not merely theoretical but deeply political and judicial. King James defends the prosecution and execution of witches, presenting them as enemies of both God and the state. His arguments helped legitimize witch trials in Britain and influenced legal and religious attitudes toward witchcraft for decades. After James ascended the English throne, Demonology gained even greater authority, reinforcing harsh policies against alleged witches. Historically, the book is significant for its impact on culture and literature. It is widely believed to have influenced William Shakespeare’s portrayal of witches in Macbeth, written during James’s reign. The text thus stands at the intersection of theology, politics, law, and art. Today, Demonology is read not as a guide to the supernatural but as a revealing document of its time. It offers modern readers insight into how fear, religion, and power combined to justify persecution, making it an essential work for understanding the history of witch hunts, early modern belief systems, and the darker consequences of absolute certainty.