Pantheism is the belief that the universe (or nature as the totality of everything) 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.
Pantheism was popularized in the modern era as both a theology and philosophy based on the work of the 17th-century philosopher Baruch Spinoza, whose Ethics was an answer to Descartes’ famous dualist theory that the body and spirit are separate. Spinoza held the monist view that the two are the same, and monism is a fundamental part of his philosophy. He was described as a “God-intoxicated man,” and used the word God to describe the unity of all substance. Although the term pantheism was not coined until after his death, Spinoza is regarded as its most celebrated advocate.
The belief that God is identical with the universe. All is God and God is all. The universe taken as a whole is God. God and Nature ( the totality of all that there is) are synonymous, two words for the same thing. (The Harper Collins Dictionary of Philosophy, Second edition, 1992)
Pantheism denotes religions which identify God with the universe. (Dictionary of Comparative Religion, 1970)
The view that God is identical with everything. It may be seen as the result of two tendencies: an intense religious spirit and the belief that all reality is in some way united. (The Cambridge Dictionary of Philosophy, 1995)