Have you ever observed somebody go through a religious conversion? The person seems perfectly reasonable to you and has no particular concern for religion. Then a parent, friend or child dies or he gets a serious illness or is involved in a car accident. In just a matter of weeks, he seeks out and finds the answers to all of life's questions and starts studying and spouting all sorts of doctrine. During such a window of vulnerability, religion can commandeer a person's brain.
"The God Virus: How Religion Infects Our Lives and Culture". Book by Darrel Ray, 2009.