The term "mystical experience" has become synonymous with the terms "religious experience", spiritual experience and sacred experience. A "religious 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.
Wayne Proudfoot traces the roots of the notion of "religious experience" to the German theologian Friedrich Schleiermacher (1768–1834), who argued that religion is based on a feeling of the infinite. The notion of "religious experience" was used by Schleiermacher to defend religion against the growing scientific and secular critique. It was adopted by many scholars of religion, of which William James was the most influential.
A broad range of western and eastern movements have incorporated and influenced the emergence of the modern notion of "mystical experience", such as the Perennial philosophy, Transcendentalism, Universalism, the Theosophical Society, New Thought, Neo-Vedanta and Buddhist modernism.