It does not give me the willies. Atheists have no basis for making any moral judgements.
Atheist does what common sense teach them to be the right things to do, that implies atheist do altruistic action from time to time.... not for fear or rewards from a deity but because atheist common sense tells them what is the right thing to do. Atheists common sense is base on literacy, education, respect for human rights and empathy toward other human beings and what is thought to be fair and just.
Moral codex is determined by the social rules and agreements on how we like to live our life with each others and in most case that means a peaceful and respectful coexistence with each others - because that is what everyone wants and needs the most... I know this, and talking from my own experiences here, because I am born, raised and educated in one of the most secular and atheist countries in the world; namely Sweden.
Sweden, as being a secular and atheistic country, is ranked among the most richest, well educated, peacefully and happiest people in the world. We share our wealth with each others, not because we have to but because we wants to; it makes people feel safer and be able to live happier lives with less worries.
If that does not tell something about moral values among atheist, I dunno what will....
In the absence of an absolute moral law giver there can be no absolute moral laws and any moral claim is reduced to subjective opinion of no more value than the next persons opinion.
That is true, but....
There is no need for an absolute moral law for the simple reason such things cannot be applied to every situation. All it needs is to function and to produce the thing we agreed we wants from it, i.e. in Sweden's case make people feel safer and happier, whether such moral code is absolute or not is irrelevant for this goal... it is about common agreement in what kind of society you like to live in. The subjective nature of moral values is what makes atheist tolerant towards other belief system; it is simply not the atheist business how you like to live your life and any one is free to form their own community with their own shared values if they like.
This because moral system is a product of the environment they exists in. Moral codex for a social cooperating system (which human are) are quite different from, say, a solitary living existence. Just look around in nature and you will notice animal uses different moral codex dependent on the social structure they are organized in.
If you like to live in society with murder, rape, thefts and discrimination (like in US of A), feel free... but we Swedes and the rest of Western Europe, as being secular and atheists, tends not to like to live our lives like that and will likely condemn or be critical toward those who make such choice for humanitary reasons.
Perhaps you now understand why we values literacy and education so highly in Sweden....