PMFJI,
There are two general ways of looking at morality. One holds that there is a single moral code that we should be able to eventually discover, and is objectively the best code to follow, because this flows naturally from the facts of the real world. The other holds that there is no such objective morality, and therefore we must meekly aquiesce to everyone else's claim to their own private moral code - a sure recipe for disaster - or invent a supernatural authority figure who can float down like a deus-ex-machina and impose an arbitrary moral code on us and intimidate us into treating it as if it really were objectively true.
To put it another way, a person who believed in God and in natural law would say, "God recognizes what is good and bad, and wants us to follow the good", but a creationist would say, "there is no good or bad, so God must come up with a good and a bad for us to follow".
Within the natural law camp, there is also a division: Those who believe our innate understanding of right and wrong was a gift from God, and those who believe this understanding simply flows logically from human nature. Consider these words from America's Declaration of Independence:
"We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness."
One camp focuses on the word "Creator", assumes it can only be a supernatural person, and concludes that if there were no such creator we wouldn't have any unalienable rights. The other camp focuses on the word "endowed", and concludes that it's our inherent status as human beings - the rational animal - that explains our individual rights, and that the specific identity of the Creator is incidental. Thus the Creator could be a purely natural process instead of a supernatural person, and a moral system based on individual rights would be just as valid and logically sound.
I believe this is why creationists are so emotionally wrapped up in tearing down a basic theory of mainstream science that happens to create problems for a specific religious interpretation, why they persist even when it makes them look silly, why they insinuate that evolutionists really want to tear down society, and why it's all so staggeringly un-persuasive to us on the evo side.