The theory of non-overlapping magisteria (or NOMA) - the idea that science and religion have authority in entirely separate domains and do not come into conflict - is, in a word, rubbish. However, it's remarkably persistent rubbish. I've written about the issue at length elsewhere, but let's deal with it in a nutshell.
According to NOMA, science tells us about the physical world while religion provides moral guidance. These are different in character, so there can never be a clash between them.
Well, if you believe that you might be prepared to call for a cessation in hostilities between science and religion, which may even sound like an attractive prospect. But the doctrine of NOMA is rotten through and through.
Historically, religions have been encyclopedic systems of belief, offering explanations of a vast range of phenomena ... as well as providing guidance for their adherents' actions. As encyclopedic systems, they inevitably come into conflict with science as the latter provides more and more facts about how the world actually works. Religion can avoid direct conflicts only by retreating into highly abstract and more-or-less unfalsifiable positions. Some modern-day versions of religion may well have retreated so far from falsifiability that they are no longer in direct conflict with science, but that's a fascinating historical development, not an indication that religion and science exercise inherently different and non-overlapping magisteria.
Even when religion avoids direct conflict with good science, and is thus not plainly irrational, it tends not to be believable when its image of the universe is held up against the emerging scientific image. In particular, who, in the light of science, can seriously adopt the orthodox Abrahamic idea of a loving and providential (yet all-powerful and all-knowing) deity? Who can believe - without having been brainwashed, or shall we say "socialised"? - that a loving and providential god is responsible for the emergence of rational beings in its divine image only after the passage of hundreds of millions of years; the extinction of countless species; various planetary catastrophes and mass extinctions; and throughout all this, ever since sentient creatures evolved a few hundred million years ago, the ever-present agony of nature red in tooth and claw?
When it comes to the moral teachings of religion, some of them are uncontroversial because almost any moral system must find a place for them: try to be kind to others; treat people honestly; settle your disputes without violence if you can. Almost any society needs to treat kindness, honesty, and non-violence (except in specific, regulated situations) as virtues rather than vices, and must have some concept of theft, fraud, and unlawful killing. It always seems anomalous - not to mention suspicious - when anthropologists claim to have discovered an isolated tribe with a radically different concept of moral virtue.
But the specifically religious content of religious morality is usually sick and miserable. It typically involves a nasty kind of ascetism; it fossilises moral injunctions from unenlightened and more economically-backward times (injunctions that were of dubious value even then, and are totally disconnected from modern needs); and it is couched in terms of an implausible absolutism that makes no allowance for circumstances, or gains flexibility only by means of bizarre doctrines such as the Catholic principle of double effect.
I was struck again by the nasty ascetism that's a legacy of our society's heritage of hundreds of years of Christian hegemony when I read a recent piece by Roger Scruton. Here, as so often, there is an assumption that asceticism has the high moral ground. Why - from any viewpoint based in reality and reason - is Scruton's word "hedonism", which he plasters over contemporary humanism, a term of shame?
As my readers know I don't deprecate the activities of art, science, and scholarship. Quite the opposite. Nor do I doubt the importance of fighting injustice. By all means let's put much of our energy into those things, in whatever ways suit our individual talents. But nor should we deprecate the pleasures of the body - the joy of dancing, the liquid velvet of good red wine, the caress of sunshine on our skin, the visual delight of beauty in its all forms, the ecstasy of sex ... I'm not going to bullied into shame about those pleasures. They are wonderful things, there to be enjoyed without reservation.
One of the most deplorable aspects of religion, as we've experienced it historically, is its pathological rejection of sexuality, the body, and ordinary physical pleasures, as if we need some excuse to engage in them. As if we thereby lower ourselves.
Religion has never, except as a strategy of retreat, restricted itself to teachings about morality ... and when it does offer its own distinctive moral teachings, the effect is usually a morality that we'd be better off without.