I'm not suggesting that you rely only on their portrayal of their own beliefs. On the contrary, I'm suggesting long and careful observation of their behavior (including professions of belief) before you reach any confident conclusion.
...And even after you've gathered many such observations, you will still be misled if you use the wrong approach in incorporating those observations into a model. Many natural-born atheists use the following fallacious approach to understanding the religious: They think to themselves, "What would it take to make me act like that and say those things? ...
Well, I'm already relying on a large data set, and I was born into a Catholic family. My theory still makes more sense. Here are some more data points:
-The parallels between religion and politics: how they force people into teams, say whatever it takes to defend the team, look for cues about whether you're on their team when they ask about your beliefs,
-The history of religious warfare. It makes no sense to view these people as going out to die for inscrutable theological doctrines, but complete sense to view their motives the same as they would be if you replaced the religion with some other memetic group.
My theory still makes more sense. Here are some more data points:
-The parallels between religion and politics: how they force people into teams, say whatever it takes to defend the team, look for cues about whether you're on their team when they ask about your beliefs,
I'd say that this data point supports my position. Get an extreme left-winger or right-winger drunk and you're not going to hear them say, "yeah, those extreme political positions I espouse, I don't really think they're true. I just pretend to because of the social benefits I reap.&...
Anticipation and faith are both aspects of the human decision process, in a sense just subroutines of a larger program, but they also generate subjective experiences (qualia) that we value for their own sake. Suppose you ask a religious friend why he doesn’t give up religion, he might say something like “Having faith in God comforts me and I think it is a central part of the human experience. Intellectually I know it’s irrational, but I want to keep my faith anyway. My friends and the government will protect me from making any truly serious mistakes as a result of having too much faith (like falling into dangerous cults or refusing to give medical treatment to my children)."
Personally I've never been religious, so this is just a guess of what someone might say. But these are the kinds of thoughts I have when faced with the prospect of giving up the anticipation of future experiences (after being prompted by Dan Armak). We don't know for sure yet that anticipation is irrational, but it's hard to see how it can be patched up to work in an environment where mind copying and merging are possible, and in the mean time, we have a decision theory (UDT) that seems to work fine, but does not involve any notion of anticipation.
What would you do if true rationality requires giving up something even more fundamental to the human experience than faith? I wonder if anyone is actually willing to take this step, or is this the limit of human rationality, the end of a short journey across the space of possible minds?