There's a reason we can all agree on theism as a good source of examples of irrationality.

Let's divide the factors that lead to memetic success into two classes: those based on corresponding to evidence, and those detached from evidence. If we imagine a two-dimensional scattergram of memes rated against these two criteria, we can define a frontier of maximum success, along which any idea can only gain in one criterion by losing on the other. This doesn't imply that evidential and non-evidential success are opposed in general; just that whatever shape memespace has, it will have a convex hull that can be drawn across this border.

Religion is what you get when you push totally for non-evidential memetic success. All ties to reality are essentially cut. As a result, all the other dials can be pushed up to 11. God is not just wise, nice, and powerful - he is all knowing, omnibenificent, and omnipotent. Heaven and Hell are not just pleasant and unpleasant places you can spend a long time in - they are the very best possible and the very worst possible experiences, and for all eternity. Religion doesn't just make people better; it is the sole source of morality. And so on; because all of these things happen "offstage", there's no contradictory evidence when you turn the dials up, so of course they'll end up on the highest settings.

This freedom is theism's defining characteristic. Even the most stupid pseudoscience is to some extent about "evidence": people wouldn't believe in it if they didn't think they had evidence for it, though we now understand the cognitive biases and other effects that lead them to think so. That's why there are no homeopathic cures for amputation.

I agree with other commentators that the drug war is the other real world idea that I would attack here without fear of contradiction, but I would still say that drug prohibition is a model of sanity compared to theism. Theism really is the maddest thing you can believe without being considered mad.

Footnote: This was originally a comment on The uniquely awful example of theism, but I was encouraged to make a top-level post from it. I should point out that there are issues with my dividing line between "evidence-based" and "not evidence-based", since you could argue that mathematics is not evidence-based and nor is the belief that evidence is a good way to learn about the world; however, it should be clear that neither of these has the freedom that religion has to make up whatever will make people most likely to spread the word.

Previously in series:  Your Price for Joining

Perhaps the single largest voluntary institution of our modern world—bound together not by police and taxation, not by salaries and managers, but by voluntary donations flowing from its members—is the Catholic Church.

It's too large to be held together by individual negotiations, like a group task in a hunter-gatherer band.  But in a larger world with more people to be infected and faster transmission, we can expect more virulent memes.  The Old Testament doesn't talk about Hell, but the New Testament does.  The Catholic Church is held together by affective death spirals—around the ideas, the institutions, and the leaders.  By promises of eternal happiness and eternal damnation—theologians don't really believe that stuff, but many ordinary Catholics do.  By simple conformity of people meeting in person at a Church and being subjected to peer pressure.  &c.

We who have the temerity to call ourselves "rationalists", think ourselves too good for such communal bindings.

And so anyone with a simple and obvious charitable project—responding with food and shelter to a tidal wave in Thailand, say—would be better off by far pleading with the Pope to mobilize the Catholics, rather than with Richard Dawkins to mobilize the atheists.

For so long as this is true, any increase in atheism at the expense of Catholicism will be something of a hollow victory, regardless of all other benefits.

Reply to: The Sacred Mundane, BHTV: Yudkowsky vs. Frank on "Religious Experience"

Edward Crowley was a man of many talents. He studied chemistry at Cambridge - a period to which he later attributed his skeptical scientific outlook - but he soon abandoned the idea of a career in science and turned to his other passions. For a while he played competitive chess at the national level. He took to mountain-climbing, and became one of the early 20th century's premier mountaineers, co-leading the first expedition to attempt K2 in the Himalayas. He also enjoyed writing poetry and travelling the world, making it as far as Nepal and Burma in an era when steamship was still the fastest mode of transportation and British colonialism was still a thin veneer over dangerous and poorly-explored areas.

But his real interest was mysticism. He travelled to Sri Lanka, where he studied meditation and yoga under some of the great Hindu yogis. After spending several years there, he achieved a state of mystical attainment the Hindus call dhyana, and set about trying to describe and promote yoga to the West.

He was not the first person to make the attempt, but he was certainly the most interesting. Although his parents were religious fanatics and his father a fundamentalist preacher, he himself had been an atheist since childhood, and he considered the vast majority of yoga to be superstitious claptrap. He set about eliminating all the gods and chants and taboos and mysterian language, ending up with a short system of what he considered empirically validated principles for gaining enlightenment in the most efficient possible way.

Reading Crowley's essay on mysticism and yoga at age seventeen rewrote my view of religion. I had always wondered about eastern religions like Buddhism and Hinduism, which seemed to have some underlying truth to all their talk of "enlightenment" and "meditation" but which seemed too vague and mysterious for my liking. Crowley stripped the mystery away in one fell swoop.

Followup to:  Is Humanism a Religion-Substitute?

So I was reading (around the first half of) Adam Frank's The Constant Fire, in preparation for my Bloggingheads dialogue with him.  Adam Frank's book is about the experience of the sacred.  I might not usually call it that, but of course I know the experience Frank is talking about.  It's what I feel when I watch a video of a space shuttle launch; or what I feel—to a lesser extent, because in this world it is too common—when I look up at the stars at night, and think about what they mean.  Or the birth of a child, say.  That which is significant in the Unfolding Story.

Adam Frank holds that this experience is something that science holds deeply in common with religion.  As opposed to e.g. being a basic human quality which religion corrupts.

The Constant Fire quotes William James's The Varieties of Religious Experience as saying:

Religion... shall mean for us the feelings, acts, and experiences of individual men in their solitude; so far as they apprehend themselves to stand in relation to whatever they may consider the divine.

And this theme is developed further:  Sacredness is something intensely private and individual.

Which completely nonplussed me.  Am I supposed to not have any feeling of sacredness if I'm one of many people watching the video of SpaceShipOne winning the X-Prize?  Why not?  Am I supposed to think that my experience of sacredness has to be somehow different from that of all the other people watching?  Why, when we all have the same brain design?  Indeed, why would I need to believe I was unique?  (But "unique" is another word Adam Frank uses; so-and-so's "unique experience of the sacred".)  Is the feeling private in the same sense that we have difficulty communicating any experience?  Then why emphasize this of sacredness, rather than sneezing?

The light came on when I realized that I was looking at a trick of Dark Side Epistemology—if you make something private, that shields it from criticism.  You can say, "You can't criticize me, because this is my private, inner experience that you can never access to question it."

But the price of shielding yourself from criticism is that you are cast into solitude—the solitude that William James admired as the core of religious experience, as if loneliness were a good thing.

Such relics of Dark Side Epistemology are key to understanding the many ways that religion twists the experience of sacredness:

I particularly remember one scene from Bill Maher's "Religulous". I can't find the exact quote, but I will try to sum up his argument as best I remember.

Christians believe that sin is caused by a talking snake. They may have billions of believers, thousands of years of tradition behind them, and a vast literature of apologetics justifying their faith - but when all is said and done, they're adults who believe in a talking snake.

I have read of the absurdity heuristic. I know that it is not carte blanche to go around rejecting beliefs that seem silly. But I was still sympathetic to the talking snake argument. After all...a talking snake?

To paraphrase the Black Belt Bayesian:  Behind every exciting, dramatic failure, there is a more important story about a larger and less dramatic failure that made the first failure possible.

If every trace of religion was magically eliminated from the world tomorrow, then—however much improved the lives of many people would be—we would not even have come close to solving the larger failures of sanity that made religion possible in the first place.

We have good cause to spend some of our efforts on trying to eliminate religion directly, because it is a direct problem.  But religion also serves the function of an asphyxiated canary in a coal mine—religion is a sign, a symptom, of larger problems that don't go away just because someone loses their religion.

Consider this thought experiment—what could you teach people that is not directly about religion, which is true and useful as a general method of rationality, which would cause them to lose their religions?  In fact—imagine that we're going to go and survey all your students five years later, and see how many of them have lost their religions compared to a control group; if you make the slightest move at fighting religion directly, you will invalidate the experiment.  You may not make a single mention of religion or any religious belief in your classroom, you may not even hint at it in any obvious way.  All your examples must center about real-world cases that have nothing to do with religion.

If you can't fight religion directly, what do you teach that raises the general waterline of sanity to the point that religion goes underwater?

Followup to: Simultaneously Right and Wrong

Related to: Augustine's Paradox of Optimal Repentance

"When they inquire into predestination, they are penetrating the sacred precincts of divine wisdom. If anyone with carefree assurance breaks into this place, he will not succeed in satisfying his curiosity and he will enter a labyrinth from which he can find no exit."

            -- John Calvin

John Calvin preached the doctrine of predestination: that God irreversibly decreed each man's eternal fate at the moment of Creation. Calvinists separate mankind into two groups: the elect, whom God predestined for Heaven, and the reprobate, whom God predestined for eternal punishment in Hell.

If you had the bad luck to be born a sinner, there is nothing you can do about it. You are too corrupted by original sin to even have the slightest urge to seek out the true faith. Conversely, if you were born one of the elect, you've got it pretty good; no matter what your actions on Earth, it is impossible for God to revoke your birthright to eternal bliss.

However, it is believed that the elect always live pious, virtuous lives full of faith and hard work. Also, the reprobate always commit heinous sins like greed and sloth and commenting on anti-theist blogs. This isn't what causes God to damn them. It's just what happens to them after they've been damned: their soul has no connection with God and so it tends in the opposite direction.

Consider two Calvinists, Aaron and Zachary, both interested only in maximizing his own happiness. Aaron thinks to himself "Whether or not I go to Heaven has already been decided, regardless of my actions on Earth. Therefore, I might as well try to have as much fun as possible, knowing it won't effect the afterlife either way." He spends his days in sex, debauchery, and anti-theist blog comments.

Zachary sees Aaron and thinks "That sinful man is thus proven one of the reprobate, and damned to Hell. I will avoid his fate by living a pious life." Zachary becomes a great minister, famous for his virtue, and when he dies his entire congregation concludes he must have been one of the elect.

Before the cut: If you were a Calvinist, which path would you take?