I gather that many people believe that atheism implies nihilism — that rejecting God means rejecting morality. A person who denies God, they reason, must be, if not actively evil, at least indifferent to considerations of right and wrong. After all, doesn’t the dictionary list “wicked” as a synonym for “godless?” And isn’t it true, as Dostoevsky said, that “if God is dead, everything is permitted”?
Well, actually — no, it’s not. (And for the record, Dostoevsky never said it was.) Atheism does not entail that anything goes.
Admittedly, some atheists are nihilists. (Unfortunately, they’re the ones who get the most press.) But such atheists’ repudiation of morality stems more from an antecedent cynicism about ethics than from any philosophical view about the divine. According to these nihilistic atheists, “morality” is just part of a fairy tale we tell each other in order to keep our innate, bestial selfishness (mostly) under control. Belief in objective “oughts” and “ought nots,” they say, must fall away once we realize that there is no universal enforcer to dish out rewards and punishments in the afterlife. We’re left with pure self-interest, more or less enlightened.
This is a Hobbesian view: in the state of nature “[t]he notions of right and wrong, justice and injustice have no place. Where there is no common power, there is no law: where no law, no injustice.” But no atheist has to agree with this account of morality, and lots of us do not. We “moralistic atheists” do not see right and wrong as artifacts of a divine protection racket. Rather, we find moral value to be immanent in the natural world, arising from the vulnerabilities of sentient beings and from the capacities of rational beings to recognize and to respond to those vulnerabilities and capacities in others.
I think I have talked about this before, but I can't find the link, so sorry if I am repeating myself. But I frequently use this analogy to explain how being a sociopath doesn't necessarily equate to maliciousness. Imagine that you are religious and that your religion compels you to eschew killing--"thou shalt not kill." You believe in your religion, so you do not kill. One day, you lose faith and stop believing. You start thinking to yourself, "I really hate how my neighbor mows his lawn early Sunday morning and wakes me up." You go to your neighbor's house and put a couple bullets in his head.
No, right? You wouldn't do that. Just because your religion was a dominant (if not primary) reason constraining your murderous impulses before does not mean that there aren't other reasons that would still keep you from killing, even if your faith failed you. Similarly, although moral compasses typically lead people to behave like a "good person," there might be other reasons that people would do "good" things besides a firm sense of morality.