Bible

"In theology, monotheism (from Greek μόνος "one" and θεός "god") is the belief in the existence of one deity, or in the oneness of God. In a Western context, the concept of "monotheism" tends to be dominated by the concept of the god of the Abrahamic religions and the Platonic concept of God as put forward by Pseudo-Dionysius the Areopagite."

—http://en.wikipedia.org/wiki/Monotheism