So, you're using Light as a metaphor and then referring to it as something physical, depending on the point you wish to make? Cherry Picking your definitions? If there was no Darkness to hold a Light, how would Light exist? No, Darkness is the Womb that Births Light, both scientifically and philosophically.
Yin Yang is a false concept of Duality, which doesn't really exist either. Perhaps this is why you keep assigning Light/Dark with Good/Evil? It just isn't so, everything is unique unto itself, there may be polar extremes, but a closed system of Duality is an illusion.
Are you going to start using the Christian bible as part of your argument? Because that would be a very bad idea given the fact that Yahweh can be construed as pure Evil along with the message of that book. It will undeniably prove that Atheists are morally and ethically above Christians, and that Man is morally and ethically above Yahweh.