A religious experience (sometimes known as a spiritual experience, sacred experience, or mystical experience) is a subjective experience which is interpreted within a religious framework. The concept originated in the 19th century, as a defense against the growing rationalism of Western society. William James popularised the concept.
Many religious and mystical traditions see religious experiences (particularly the knowledge which comes with them) as revelations caused by divine agency rather than ordinary natural processes. They are considered real encounters with God or gods, or real contact with higher-order realities of which humans are not ordinarily aware.
Skeptics may hold that religious experience is an evolved feature of the human brain amenable to normal scientific study. The commonalities and differences between religious experiences across different cultures have enabled scholars to categorize them for academic study.