Very Intelligent Yet Very Religious? The most puzzling dichotomy

I have a few very smart friends. They excel in math, english, science and score higher than me on tests. I would say they have great reasoning and analysis skills as well. They sound intelligent in every field but religion. The smartest person I know honestly asked me "If we came from monkeys then why are monkeys still here?" First of all, we have the same common ancestor. That's like asking if we came from the same grandparents then why are our cousins still here. My other friend, the Soluditorian of my school, couldn't be more of a crazy conservative catholic even if he tried. So my question is why are some of the smarter people I know, so religious? It makes me wonder if they're actually smart.