I would substitute the words "self importance" with "self worth." In a godless, evolutionary universe, the human has neither importance nor inherent worth, so anything goes: murder, rape, torture, etc. After all, if we are only animals, why should we act any differently than animals?
I think that's a false argument, though I've seen many theists make it. The
Euthyphro dilemma aside (i.e. the question of whether morality and goodness flow from God, or exist independently), your moral nature is not dictated by your physiology or your evolutionary history.
Your rationale has a few implicit steps, so I'll break it down so they can be addressed:
- animals are amoral
- evolutionary theory is incompatible with morality handed down by God.
- if evolutionary theory is correct, then humans are animals as well, and have no God-given morality.
- therefore, if evolutionary theory is correct, then humans would be amoral.
- therefore, if evolutionary theory is correct, there is no reason for humans to act morally.
Physiologically, humans
are animals, regardless of your beliefs about how we came into being. As evidenced by the fact that humans are capable of exercising morality, we can conclude that this fact does not automatically imply that humans are amoral creatures.
Further, I don't see why only a scenario where Adam and Eve are created whole by the direct hand of God is the only one where God would be able to endow humans with morality. What reason do you have for this assumption that, IMO, is built into your question?
Still further, even without any sort of morality handed down by God, a code of human social behaviour would still settle out... even an amoral creature will still try to acheive maximum benefit for itself, and in most social settings, indiscriminate raping and killing will work against that goal, not for it. Also, evolutionary theory predicts that over time, beneficial behaviours will tend to become more prevalent, and detrimental ones will become rarer and rarer. Assuming that it was beneficial for our ancestors to live in groups, behaviours and traits that help us work better as a group will tend to be favoured, whether they're passed down through genetics or through parents teaching their children.
It may be argued that animals might not have "morality" as we define it, but they do have norms of behaviour that discourage certain types of conduct and encourage others. Making a distinction between this and human morality might be only semantics, or excess anthropocentrism.
So... even without God, we'd still end up with some sort of moral code. And even without direct special creation, I imagine that an omnipotent God would be able to find
some way to imbue morality into us if He thought it was necessary.