One of my regular commenters asked, in a previous thread, “If everyone was truly released from the shackles of religion, and got beyond the false moral codes imposed on them, would society collapse in a heap of nihilism?” This question needs a longer answer that will fit in a reply comment.
The shortest summary is “No!”. The less short answer is: “No, because religious moral codes are epiphenomenal.” And it is on point to add that the question reveals serious ignorance of the actual traits of most religions over most of history.
I’ll address the historical point first. The commenter’s question was framed from within the assumptions of one particular family of religions: the Judeo/Christian/Islamic tradition, which are more succinctly describable as the bastard offspring of Zoroastrian dualism. In this family, “religion” bundles cosmology, theology, and morality into a single total system designed primarily to enforce norms by programming the believer with an internalized guilt machine.
Because the dominant religions of the modern West are all derived from this group, it is difficult for Westerners to understand how bizarre and exceptional these religions are in a broader context. Most religions are not total systems. Most religions do not tie morality to cosmology. In fact, most religions have very little to say about morality at all!
Consider, for example, an Altaic shaman. It’s not his job to pronounce on who should sleep with who, or to tell people that theft is wrong. It’s not even his job to tell people that they must worship Tengri or Kara-han; dealing with the gods is his specialty, thank you. His job combines aspects of psychologist and medic with a bit of divination. The closest analog of “morality”, in his culture, is a set of inherited customs and taboos which is reinforced by explanatory myths but not generated by them and not really dependent on them. The closest equivalent of religious structures about right and wrong is an elaborate set of rules about ritual purity and impurity. In the jargon of the field, his religion is an orthopraxy rather than an orthodoxy.
Over most human cultures in most human history, “religion” has been much more like Altaic shamanism than like Christianity, Judaism, or Islam. Er, so why didn’t these cultures “collapse in a heap of nihilism”? The same question actually applies to modern religions outside the post-Zoroastrian family. Buddhism and Hinduism, for example, are almost completely unconcerned with “morality”. Hinduism is organized around ritual purity and impurity; Buddhism’s quest for merit is about liberation of the self from attachments, not about duties one owes to God or others.
Here’s another clue. One of the most pervasive taboos worldwide is against having sex with your near relatives. While religions almost never explicitly forbid this, you’d have a very hard time finding anyone who thinks it isn’t deeply wrong and icky. So: not only do lots of people have religions that don’t teach them any “morality” in the sense modern Westerners understand the term, there are near-univeral moral rules that religions don’t have a central role in propagating.
The correct way to understand religious moral codes is as epiphenomena; they’re built on top of evolved adaptive responses that predate any particular religion, and probably predate religion itself. Those of our ancestors for whom incest was not taboo inbred themselves out. The Ten Commandments may say “Thou shall not bear false witness”, but it is likely that the minds of social primates have included a cheater-detection module for five thousand times longer than the Ten Commandments have existed.
Societies without religious morality don’t “collapse into nihilism” because religion isn’t the basis of morality. “Morality” is accumulated knowledge about how not to screw up your genetic line’s reproductive chances; this is almost though not quite the same as how not to screw up your kin-group’s or tribe’s reproductive success, and the difference can be safely ignored in this context. Religions come and go without changing more than the superficial details.
The collapse of religious authority could lead to nihilism only if moral rules were fundamentally arbitrary. But they aren’t. If you have sex with your near relatives, many of the children will have serious recessive defects. If you steal from others, sooner or later a posse’s going to come around to take back the stuff and beat the crap out of you. If you tell lies, people won’t trust you and won’t come through for you when you need them. None of these rules depend on which gods you worship, or whether you have any at all.