It's a difficult thing, and I think rightly so in a pluralistic society like ours, to say one would never vote for a candidate do to some demographic characteristic. While this would not be the case for me 99% of the time, I'd have no trouble voting for a homosexual, Muslim or atheist, I don't know if I could ever vote for a Scientologist. Where prejudice meets discernment is difficult to say. I can't say that a persons mostly deeply held convictions about the nature of the universe don't matter when judging their fitness for office, though I think most people holding and seeking public office in this country are reasonably good at keeping there policy and religious spheres separate (not to say there's not room for improvement on this front). While 'anti-Mormon prejudice' is not a good thing and supposedly liberal people are often hypocritical on this issue, its still a question of exclusion by belief rather then exclusion by genetics (race, gender, and in most cases sexual preference) and is thusly a lesser prejudice then those that dominated American culture not so long ago.