Pantheism is the belief that all reality is identical with divinity, or that everything composes an all-encompassing, immanent god. Pantheists thus do not believe in a distinct personal or anthropomorphic god.
In the West, pantheism was formalized as a separate theology and philosophy based on the work of the 17th-century philosopher Baruch Spinoza, whose book Ethics was an answer to Descartes' famous dualist theory that the body and spirit are separate. The term pantheism was not coined until after Spinoza's death, but he is regarded as its most celebrated advocate. His work, Ethics, was the major source from which Western pantheism spread.
Pantheistic concepts may date back thousands of years, and some religions in the East continue to contain pantheistic elements.
Pantheism derives from the Greek πᾶν pan (meaning "all, of everything") and θεός theos (meaning "god, divine").
There are a variety of definitions of pantheism. Some consider it a theological and philosophical position concerning God.
As a religious position, some describe pantheism as the polar opposite of atheism. From this standpoint, pantheism is the view that everything is part of an all-encompassing, immanent God. All forms of reality may then be considered either modes of that Being, or identical with it. Some hold that pantheism is a non-religious philosophical position. To them, pantheism is the view that the Universe (in the sense of the totality of all existence) and God are identical (implying a denial of the personality and transcendence of God).
Pantheistic tendencies existed in a number of early Gnostic groups, with pantheistic thought appearing throughout the Middle Ages. These included a section of Johannes Scotus Eriugena's 9th-century work De divisione naturae and the beliefs of mystics such as Amalric of Bena (11th–12th centuries) and Eckhart (12th–13th).