People have multitude of reasons for and against religion. The epistemology of faith, the (false) reassurance that something can be held to be true, became incompatible with the evidence which I came aware of.
It is not that we as humans are impeccable logical beings (because I know that my mother simply stops talking, when I point flaws in her beliefs or simply retreats to usage of Orwellian double-thinking), it is because we are able to hold illogical ideas without identifying the faults. And there are two "modes", the willful un-acknowledgment (denial) and the ignorance. For example today are a lot of modern superstitions, but people are not conscient that what they believe to be true are in reality superstitions, either because they don't know enough about them or that they have simply accepted them as true (this is epistemological similar to faith).
One concrete example of modern superstition, is that we must always dress in warm cloths in the winter otherwise one is more likely to catch a cold. The reality is that it does not matter if you're warm or cold; when you get exposed to an influenza virus you're likelihood to catch a cold is equally the same, regardless if you're cold or warm. Other factors, such as poor physical health (don't exercise) and smoking increase receptibility.
"Contrary to popular belief, cold weather neither increases your susceptibility nor alters the course of a cold. How ever, stress and cigarette smoking seem to make symptoms more severe."
http://abrannen.home.mindspring.com/alag/colds.htm
Although people deny it, superstition and faith have a common denominator; a belief in validity (often it is dogmatic). It is only when a doctor researched into the conditions of influenza that the reality of the conditions for catching the common cold became more evident.
Everyone has reason. It is just what we can reason about, which is important. If you don't test common beliefs, then how can you be sure that they are true? Well, you can't. There is no escaping that.
This leaves the question, how do you test a belief? That is where the empirical testing method is one of the best methods to ascertain validity. Logical testing (thesis -> antithesis -> Synthesis) and theory are the ones which make us able to interpret an empirical test. Note that theory and empiricism are not contingently related (you can have a theory without tests, and have tests without understanding of the systemization behind the tests).