Aleister Crowley, a British occultist created a spiritual philosophy called Thelema, which emphasizes the idea that each person should follow their true will or purpose in life. His teachings blended elements of magic, mysticism, and personal freedom.

Crowley is best known for his work on ceremonial magic, which involves rituals and spells meant to bring about spiritual or personal transformation. His books, especially The Book of the Law, have been influential to many modern occultists and some Satanists. Though Crowley didn't identify as a Satanist, his writings have been adopted by some theistic Satanists, who see his ideas about power, rebellion, and self-deification as aligning with their beliefs.

Many of Crowley’s practices and ideas about magic and self-empowerment were groundbreaking, and they helped shape the way modern occult groups think about spirituality, the supernatural, and individual freedom. Some Satanists see Crowley’s work as a guide to understanding and harnessing personal power, viewing Satan as a symbol of defiance and personal strength—ideas that Crowley explored in his writings and practices.