OK, if we go there, this will turn into a theological discussion in the wrong place. However, to answer your question...you're assuming there was a universe without light. I don't know what your exact opinion of how the universe came into being is, but many have light being there from the beginning. Even if they don't, I'm not sure what difference that makes. How dark something is, does not depend on how much darkness there is, it depends on how much light there is not.
Or, to put it much shorter, what kills said.