I'm aware of survey data demonstrating an inverse correlation between education and religiosity. I'm not sure this equates to 'smart people are areligious and less smart people are religious.' In fact, I'm very hesitant to draw this conclusion, except to note that general trend support the notion that education and tendency toward religious belief are not unrelated.
Personally in my circle of family, friends and acquaintances, I know many very intelligent people who ardent believers, so at the very least, high intelligence and religious belief are by no means mutually exclusive. (By religious belief here, I am referring to adherence to some kind of religious belief system as codified by a particular organized religion or sect.)
There is a great deal of writing and research on why presumably smart people believe in 'strange' things. Here's a link to an article describing some of this research: https://www.newyorker.com/tech/frontal-cortex/why-smart-people-are-stupid. A quick Google search will uncover much information on this topic.
One source I recommend is Michael Shermer's "Why Smart People Believe Weird Things." (Shermer is one of my favorite authors.) In a nutshell, smart people are very good at explaining/rationalizing beliefs arrived at by unsound means. There is a good deal of research to support this conclusion. I looked for a summary of one study I'm aware of that looked precisely at this, but I couldn't find it in the brief time I allowed to the search. To my mind, one of the best forums to see this phenomenon at work is among the LDS apologists--very smart people who have developed quite sophisticated, at times, methods to explain away problems with LDS history and beliefs (and at times quite silly methods). I would bet that few of these apologists would be willing to apply the same reasoning to explain beliefs they disagree with and would find efforts by others to do so lacking.
Thus looking to verify one's own beliefs by appealing to authority in the guise of a very smart person is probably not a sound way to proceed. Smart people can and do believe in all sorts of sh**.
I've met Shermer is real life. Let's just say that he's not a very nice person.
