Most of the people I've known in my life were pretty rational about most things, regardless of whether they were "religious" or not. Most of them had little trouble recognizing facts, understanding physical reality or engaging in rational thought. Most of them agreed on known facts, such as are presented in math, science, etc...while they disagreed on much more subjective matters, matters which cannot be substantiated by fact.

Further to that, most of them were irrational about a certain few things...again, regardless of whether they were "religious" or not. ;-)

Therefore, I think all this ballyhoo about rationality (as if it could be determined by whether or not a person is religious) is a waste of bandwith.