(Off-topic) You could probably edit out the drug war bit.
(Note) This was originally supposed to be a comment in response to the same post ciphergoth was responding to. After a while it bloated into something not directly related to the original post and so I just saved it somewhere until it was more relevant. I think it actually fits this post better but the whole thing is only slightly related to the topic.
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.
This is strictly only useful when talking to someone who believes that specific set of beliefs. What if the religion believes in an evil God? A God that can be tricked? What it believes we are the Gods? Any or all of these could be just as irrational, but they are instantly excluded from the argument and any theist who does not perfectly fit the example can just shrug it off and say, "oh, it does not apply to me." That does not seem particularly useful, but I watch communities of rational atheists stand and nod their head like the ultimate truth has been spoken even though it only applies to a strict subset of theistic beliefs.
There are huge swaths of major religious theory that are blatantly irrational. Some world religions even take the irrationality as a core feature and emphasize its own inability to be rationally processed. There is, however, a strong tendency to look at these logic evils, denounce them, and then throw the rest of Earth's theology into the same category of "obviously stupid".
(Minor point) I am not saying that the rest of Earth's theology doesn't belong in the category of obviously stupid. I am saying that I watch a lot of people (not necessary people here) start throwing things into that bucket irrationally. Whether they end up there eventually is irrelevant.
The most prevalent examples are posts that apparently assume folk-Christianity as the one religion. To unfairly pick on someone, your post is an example. To claim that "theism" works a certain way and then only give one, albeit common, example of theism is a little shortsighted. Your point is wonderful and useful, but it does not apply to all of theism.
The problem is not that you found something irrational about theism. The problem seems to be that much of what is said about the invalidity of religion is assumed to be true or rational. In other words, I see this:
Belief A is a known problem and has been denounced by the throngs of rationalists.
Belief B looks suspiciously similar to Belief A and is denounced out of hand by the same throngs.
To express this pattern with a non-theistic example:
Pascal's Wager is a known problem and has been denounced by the throngs of rationalists.
Arguments for cryonics looks suspiciously similar to Pascal's Wager and is denounced out of hand by the same throngs.
This pattern is directly addressed by Eliezer's The Pascal's Wager Fallacy Fallacy and is also talked about in Roko's Rationality, Cryonics and Pascal's Wager.
In the case of cryonics, Eliezer and Roko argued that cryonics deserves another shot. In the case of theism, I am not saying any particular belief deserves another shot, I am just reminding the community as a whole that "irrational by association" is a fallacy.
(Side topic) One possible response to this, in my opinion, is that theism is rotten at its core. Theism, all variants, have been denounced as irrational and nitpicking over specific examples just slows everything down. Someone who is a theist happened to miss the memo. I am not suggesting nitpicking everything because most of it does not matter. This was true in the example of your post: nitpicking really has little value since the point he was making still stands. Generally speaking, one-off comments do not have a scope was intended to cover challenges to the assumed truths about theism, which is why I avoided posting this comment until you made it the subject of a full post.
(Necropost)
(Off-topic) You could probably edit out the drug war bit.
Why? I was quite glad to see it. The drug war is a "uniquely awful" example itself, being something no longer based on evidence but manufacturing it, and worse - perhaps humorously so, if only it were fiction - causing the very things it supposedly acts to prevent: death, disease, suffering, economic and social cost, and drug addiction. (Yes! Portugal and Prague show us what happens when personal use is decriminalized: fewer drug users!).
Religion is the most exaggerated one ...
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.