Oh that's easy, it's their faith in their anti-gay beliefs.
Suppose that, for no reason, I take it as Gospel that one subset of people which doesn't categorically hurt anybody is capital-E Evil. When I try to tell people my Truth about how they and their loved ones are Evil, they tell me I'm wrong and call me, 'bo*mer.' This inexplicable treatment that I receive is called, 'bigotry' and it must end