Morality is local and global rather than universal or absolute. For example, let's say you have a group of robots that are programmed to hurt each other - in that case, for the robots, causing harm would be the moral thing to do. Even if you created them, you wouldn't be justified to say that what they are doing is immoral, because you aren't a robot and you don't directly interact with them. They're independant.
Each person has morals, each group of people have morals, and eventually, all of humanity has morals. The morals of a system only guide the interactions between its different parts. It doesn't make much sense to say they come from God, because God just isn't part of humanity. It's "out there", but we have our own independant identity ("he" gave us "free will"), and therefore, we have our own independant morals. An entity can have moral authority over humans, and vice versa, if and only if if it directly interacts with other humans.