monist

n. supporter of the principles of monism

Monism is the metaphysical and theological view that all is one, that there are no fundamental divisions, and a unified set of laws underlie nature.Monism is to be distinguished from dualism, which holds that ultimately there are two kinds of substance, and from pluralism, which holds that ultimately there are many kinds of substance. Monism is often erroneously seen in relation to pantheism, panentheism, and an immanent God. The concepts of absolutism, the monad, and the "Universal substrate" are closely related as well.
See more at Wikipedia.org...

n. monist, supporter of the principles of monism

(n.)
A believer in monism.
  

monist