Good is better than bad
Even atheists (for example) offer principles for a moral code based on, usually, something like utilitarianism: of doing things that help others and not doing things that hurt others. But this assumes, I think, a universal value that good is better than bad.
I sometimes hear people claim there are no moral absolutes, and they give freak examples of when it might be morally good to do things otherwise bad. (They have to base their case on these kinds of freak examples — I would be embarrassed to believe something only provable this way.) But pushing the boundaries doesn't prove their point, rather, it merely proves that there are extreme cases in which the rules are difficult to discern.
No one wants a society in which everyone is bad and, in fact, such a society would disintegrate. Therefore, it seems to me that reality has a built in preference for "the good", call it God if you will.
Good and bad are not equal and opposite manifestations of the same thing, a yin-yang, if you will. Bad is a corruption of the good. Good is, well,... good.