Last night I saw a dude down on 3rd Street with a slide projector and a microphone. He was arguing that atheism is philosophically absurd, and morally untenable, and that macro-evolution is unproven, and such. It made my blood boil a bit, but I didn't go over to yell at him, because I didn't want to validate him, and I also didn't want to waste my time.
But I think an interesting point is raised, which is a little bit orthogonal to our specific cultural differences. I know from personal experience that many atheists are perfectly ordinary and ethical (I would also say moral) people. They function well in society, they don't go around murdering people or stealing, even when they can get away with it. So my anecdotal personal experience seems to refute the claim that atheism leads to anarchy. Maybe I've constructed a straw man here, but indulge me. The point is this: I think that moral behavior is more a function of human nature than it is of the presence of a ideological moral framework.
So, when someone has to make a moral decision, say, whether or not to steal something, I don't believe they generally consult their ideology*, I believe they consult their animal emotions. I think that's the main reason that most atheists don't end up in jail. Importantly, I think that's the same reason that most Christians don't end up in jail. People are social animals, we have an innate emotional need to be loved, and when our loved-ones feel good, we feel good too. For ordinary decisions we don't ask "what would Jesus do?" or "What will make the best society?" Mostly we act out of habit, or on our social and emotional intuition.
So while I think it's possible, and maybe even important, to derive a moral framework without relying on religion (see first post), I think an equally important realization is that our moral ideologies interact with our day to day lives only rarely**. Still, it's nice to have one when some street preacher is metaphorically calling you a piece of dysfunctional shit.
* Here I use ideology to mean their logical construction of morality founded on some fundamental faith.
** Similarly, algebra is a very basic mathematical tool, but I almost never use it, and I wrangle logic for a living. Forget about calculus. What is with that?