Card is a Mormon and I have no problem with his belief that homosexual behaviors are wrong. Tolerance is different from belief though and if he doesn't practice tolerance, why should he expect people to tolerate his religion-based beliefs?
One problem I see is that so many times, beliefs are also linked to hatred. There's really no place for hatred when two parties are trying to practice tolerance.
There's a big difference between saying "Gay marriage is bad and people who support it should feel bad" and "A government which allows gay marriage must be overthrown by any means necessary." The former I can ignore, the later not so much.
Using another picked on minority, I don't consider a "casual" neo-nazi skinhead and a dedicated one to be on particularly different levels. They both disgust me fairly equally (if for no other reason, then because the former incubate and insulate the later.)
One problem I see is that so many times, beliefs are also linked to hatred. There's really no place for hatred when two parties are trying to practice tolerance.