Second, evidence shows that religious people are happier. Now, this happiness research is of course murky, and we should hesitate to make any grand conclusions on the basis of it. But if it is true, it is deeply problematic for the kind of rationality you are advocating. If rationalists should "just win", and we equate winning with happiness, and the faithful are happier than atheists, then we should all stop reading this blog and start going to church on Sundays.

I think Eliezer Yudkowsky already addressed this point several times on "that other site" (Overcoming Bias). Basically "happiness" is a nice-sounding one word summary of "what people want", but it's inaccurate.

Look at the examples of the wish-granting genie/AI. If you wish for "happiness", it'll turn you into a pile of orgasmium, basically grey-matter which just experiences infinite pleasure constantly. You've got happiness, but it seems like it's not what most people actually want.