The book affirmed the existence of witches with malign supernatural powers of magic, and attacked scepticism concerning their abilities. Glanvill likened these sceptics to the Sadducees, members of a Jewish sect from around the time of Jesus who were said to have denied the immortality of the soul.
The book strongly influenced Cotton Mather and was influential in the Salem witch trials in Salem, Massachusetts. Mather's Wonders of the Invisible World is largely modelled after this book and its arguments. The book is also famous for telling the ghost story of the Demon drummer of Tedworth, an early poltergeist story.