Revlgking wrote:

"Dualism is the view that two fundamental concepts exist, such as good and evil, light and dark, or male and female. Often, they oppose each other. The word's origin is the Latin dualis, meaning "two" (as an adjective)."

The word's origin might be Latin but the belief is Zoroastrian. Cyrus was Zoroastrian and from his time it seems to enter Jewish belief. From that it entered Christianity, probably via Mithraism.