Intelligent people are in every religion. Does that validate any Religion they belong to? To the contrary, many people who are less intelligent refuse to believe the religious fairy tales and are neutral.
I think it all relates on a case to case basis. Every one in any religion would be having their own cause to stay in their religion. Like... Fear of life and death, Family tradition and fear of becoming an outcast if they leave, fantasies like heaven that they can cling upon.... and the list goes on