I have read "Politics is the mindkiller" and am discussing the same metaphor. For that matter, I'm practically recapitulating the same metaphor, to make an even stronger point: not only can politics provoke irrational impulses to support poor arguments on your "side", politics can create instrumentally rational incentives to (publicly, visibly, not internally) support poor arguments. Sometimes you support a morally dubious soldier because of jingoism, sometimes you support him because he's the best defense in between you and an even worse soldier.
Would you be more specific about how you think my use of the metaphor is different and/or invalid?
I do think I've given a compelling counterexample to "bad ideas should always be [publicly] challenged". (my apologies if the implicit [publicly] here was not your intended claim, but the context is that of a proposed public discussion) Have you changed your mind about that claim, or do you see a problem with my reasoning? For that matter, in my hypothetical political forum would you be arguing for atheism or for more compassionate augury yourself?
The preposition of your second sentence suggests a miscommunication of my initial claim. I didn't intend to say "arguments are soldiers of democracy", but rather "arguments are soldiers in a democracy". You're still right that this also applies to non-democracies: in any state where public opinion affects political policy, incentives exist to try and steer opinion towards instrumentally rational ends even if this is done via epistemically irrational means. Unlimited democracy is just an abstract maximum of this effect, not the only case where it applies.
In brief, I think my interpretation is right because it is consistent with the intended lesson, which is "Don't talk about Politics on LessWrong." In other words, I understood the point of the story to be that treating arguments as soldiers interferes with believing true things.
I agree that "bad ideas should be publicly challenged" is only true if what I'm trying to do is believe true theories and not believe false theories. If I'm trying to change society (i.e. do politics), I shouldn't antagonize my allies. The risk is that I will ...
Summary: I propose we somewhat relax our stance on political speech on Less Wrong.
Related: The mind-killer, Mind-killer
A recent series of posts by a well-meaning troll (example) has caused me to re-examine our "no-politics" norm. I believe there has been some unintentional creep from the original intent of Politics is the Mind-Killer. In that article, Eliezer is arguing that discussions here (actually on Overcoming Bias) should not use examples from politics in discussions that are not about politics, since they distract from the lesson. Note the final paragraph:
So, the original intent was not to ban political speech altogether, but to encourage us to come up with less-charged examples where possible. If the subject you're really talking about is politics, and it relates directly to rationality, then you should be able to post about it without getting downvotes strictly because "politics is the mind-killer".
It could be that this drift is less of a community norm than I perceive, and there are just a few folks (myself included) that have taken the original message too far. If so, consider this a message just to those folks such as myself.
Of course, politics would still be off-topic in the comment threads of most posts. There should probably be a special open thread (or another forum) to which drive-by political activists can be directed, instead of simply saying "We don't talk about politics here".
David_Gerard makes a similar point here (though FWIW, I came up with this title independently).