Expanded from a reply to a post in
jaylake's journal ("
Where should the rules come from?")
The problem is that the examples offered of attempted atheist reorganizations of society, in particular totalitarian Communism but also (for some values of "atheism") various kinds of Fascism, are frightening. Not so much because a society with atheist roots has to be totalitarian, but because abandoning the superstitious fear of sins (particularly murder) for fear of punishment does not necessarily mean gaining an enlightened concept of avoiding sins because they are destructive.
I'm not sure if human beings, as our culture and perhaps biological nature are presently constituted, can make a stable society without superstition to guard its bases. This depresses me, but my study of history makes me fear that it is true.
The closest that any society ever came to succeeding at such a goal was the United States of America, and now our Constitution is plainly dying: prominent figures are asking "why should we still care about the Constitution" and they are not being scoffed into silence, which means that a lot of people are having this thought. (That they will learn why they should have cared if we are foolish enough to scrap our Constitution is small comfort to me, schadenfreude would not make up to me for the loss of my own freedoms).
Humans have a deep-seated religious impulse. If we do not focus it on a supernatural god or gods, we tend to make gods out of prominent human beings: celebrities, politicians, generals, presidents. And when we do that, we're just one unscrupulous and charismatic man away from totalitarian dictatorship.
Another problem is that, even on the smaller scale, humans tend to treat each other worse when they have no background in religious values. We tend to overestimate the worth of anything we find pleasurable, and underestimate its cost, and so when we try to be perfectly rational we often behave hedonistically and throw away long-term gains in pursuit of short-term amusement. Religious values, grounded in the fear of a supernatural being, tend to backstop our own rationality, giving us an additional reason not to lie, cheat, steal, and so on. This works in our own self-interest.
Of course here a deeper problem emerges. There is no guarantee that the set of religious values we are raised with will happen to be constructive ones. There is a tendency (because of memetically-based cultural evolution) that they will be useful, but the environment which they may have evolved to aid survival in may be an environment radically different in key ways than the modern environment. When we think "religious" we tend to think of rational modern Christians and Jews, but "religious" also well-describes the Islamists, or the Inquisition.
There may be no good solution to this problem, other than further cultural evolution for the human race.