The interesting thing about symbols is that they have many different meanings and these change over time. Indeed, the cross of Leviathan is often used by Satanists, but at least as far as I can understand it, it is not necessarily 'their' symbol. The meaning I was hoping to refer to is that a person can be a source of truth and balance for themselves.

I don't know much about Taoism, unfortunately, except that it is very much divided into multiple, often quite different, factions. However, the idea of yin and yang, good and evil as two parts of the same thing feels right, if I understand it correctly of course. In the end, there is a little universe inside each of us, with all the light and all the shadows :)