A note

"morality itself cannot be sustained without the support of religious beliefs."

"I’ve always regarded this as a bizarre and chilling sentiment that ought to make us seriously doubt the character of anyone who utters it. Because insofar as it tacitly makes a claim about people’s incentive to behave morally, it amounts to an admission that the speaker simply cannot fathom why someone would treat others with consideration and respect"

A recent debate has once again illuminated that this is a common thread, particularly within the evangelical religious community. Apparently it's impossible to sustain basic human decency once you abandon religious dogma, and the rejection of absolute religious certainty as the only source of truth leads people to... I guess start having sex with livestock and shooting the neighbours infants after tossing them skyward or something. I have no idea how one draws the conclusion that a pro-choice (or rather a pro-abortion) position follows from "believing" in evolution, rather than believing in creationism. Because this does not follow logically without a series of other assumptions. But apparently once that "dark path" is accepted, all sorts of things are suddenly made possible that are otherwise somehow closed (based apparently on the assumption that all religious belief has the same moral flavors wrapping them up)

Given that many of the people I've encountered in the born-again/evangelical type of Christian do seem to have rather sketchy pasts (bouts with abusive use of drugs, alcohol, violence, etc), it does seem more accurate to question the person who would make this statement, this idea that only through religion is morality made possible. Based on my understandings of anthropology, the chicken in this case came first anyway. Morality, in the sense of the organisation of human societies with a set of basic rules of conduct, precedes religion. Religion simply represents a set of codified rules, and often those of a particular region, and of a particular time (and based on that time's understanding of the world).

Stripping aside these contexts, and attempting to make these types rules universal doesn't work very well. With good reason: it's not universally "moral" not to eat pork, or shellfish, or drink alcohol, or engage in pre-marital sexual relations, and so on. These are cultural cues and mores. There are arguments for some of them, some better than others, but they're not applicable to everyone. Not everyone benefits under a society with these sorts of rules (not even the pigs and shellfish, which benefit from their utility to human beings as food by becoming more populous).

As a result, when I start seeing people claim that (their particular brand of) religious piety is the only source of moral conduct, I usually know to avoid meeting this person in a dark alley.