Assorted dualisms

The Christian idea of an all-"Good" God vs. an all-"Evil" Devil is derived (via some short-lived sects of Judaism such as the Essenes) from Zoroastrianism, the religion of ancient Persia. Zoroastrians believed that the universe was ruled by two rival gods, Ahura Mazda, God of Light, and Ahriman, God of Darkness. Zoroastrians believed that these two gods would war with each other until the end of time.

Quite a few theistic Satanists believe in some variant of the idea that the universe is ruled by two rival gods (or groups of gods) in perpetual war with each other over something having to do with us humans.
Some theistic Satanists believe in the exact reverse of the Christian/Zoroastrian idea. They believe in a cosmic dualism, but with Satan/Lucifer as the good guy.

Others don't necessarily see Satan as the good guy. Some see their own side as "evil" in some sense, and others see the dualism in terms of something other than "good" vs. "evil."
The Church of Azazel does not believe in a cosmic duotheism of any kind. (See A brief critique of Christian-based duotheism.) We don't regard the Christian god as a true cosmic God. We likewise regard Satan as the "God of this world" -- possibly local to the Earth.

The human mind has a natural tendency to find patterns in everything. Our ability to find patterns is an absolutely crucial aspect of human intelligence. However, our minds have a tendency to overdo it, and to see patterns that aren't really there or don't really mean anything.

In particular, our minds have a tendency to overdo the simplest kind of pattern -- duality. An example is the tendency of many poeple to put everything they disapprove of into one box, e.g. some hardcore Christians calling all non-Christians "Satanists." Plenty of real dualities do exist, but plenty of other dualities are oversimplifications of reality. So, it's wise to be wary toward all forms of dualism.