Why do atheists deny that they are just biorobots?

[Neo-Scholastic]

Such as? You're big on the empty rhetoric; not so much on the substance.

Perhaps so. I have learned that as a general rule some people have reached various conclusions based on their atheism. Then when pressed to define those conclusions, they back away into the "no, no, atheism is simply the lack of belief." I suppose it is fair to say atheism doesn't really mean anything other than that disbelief, but it seems to serve many very well as a springboard for various doctrines like naturalism, moral relativism, and fatalism. When that is the case, I think it petty when someone focuses on semantics and not really defend the issues he or she are promoting.