Dualistic cosmology
Moral dualism is the belief of the great complement of, or conflict between, the benevolent and the malevolent. It simply implies that there are two moral opposites at work, independent of any interpretation of what might be "moral" and independent of how these may be represented. Moral opposites might, for example, exist in a worldview which has one god, more than one god, or none. By contrast, duotheism, bitheism or ditheism implies (at least) two gods. While bitheism implies harmony, ditheism implies rivalry and opposition, such as between good and evil, or light and dark, or summer and winter. For example, a ditheistic system could be one in which one god is a creator, and the other a destroyer. In theology, dualism can also refer to the relationship between the deity and creation or the deity and the universe (see theistic dualism). This form of dualism is a belief shared in certain traditions of Christianity and Hinduism. Alternatively, in ontological dualism, the world is divided into two overarching categories. The opposition and combination of the universe's two basic principles of yin and yang is a large part of Chinese philosophy, and is an important feature of Taoism. It is also discussed in Confucianism.
Kabbalah
Although Kabbalah propounds the Unity of God, one of the most serious and sustained criticisms is that it may lead away from monotheism, and instead promote dualism, the belief that there is a supernatural counterpart to God. The dualistic system holds that there is a good power versus an evil power. There are two primary models of Gnostic-dualistic cosmology: the first, which goes back to Zoroastrianism, believes creation is ontologically divided between good and evil forces; the second, found largely in Greco-Roman metaphysics like Neo-Platonism, argues that the universe knew a primordial harmony, but that a cosmic disruption yielded a second, evil dimension to reality. This second model influenced the cosmology of the Kabbalah.