I never said that utility and truth are mutually exclusive. I said that a society that values utility over truth is less likely to value justice and freedom.
The most obvious fact that argues against the truth of religion is that they can't all be true. We have all of these people throughout history (Paul, Mohammed, Joseph Smith, David Koresh etc) who have claimed to have special knowledge directly from god or someone sent as a messenger of god.
If you are religious that means that you believe EVERY one of these men were liars EXCEPT for the one you believe is true. Isn't it much more reasonable that ALL of these men were liars and conmen? That all of them were using the idea of god to gain power? Maybe some of them even believed their own stories, because of the power they had over other people. But, the fact people will believe in anything that gives them hope doesn't make it more true.
I am more than willing to let people believe what they want to believe. But, it upsets me when someone who could possibly be our next president says that a society must believe in these stories (even if people believe in stories that contradict each other) in order for there to be freedom in that society. I think that a society must value Truth in order to have freedom and justice - believing in stories made up by other men has nothing to do with valuing freedom - and it scares me that we even have to debate that point.