Rationality
The idea that the Democrats represent the height of rationality doesn't stand up very well either. There are one hell of a lot of things that can be believed that "Just Ain't So" that have nothing to do with conventional religion, and many of these irrational beliefs have killed a lot more people than religion ever did.
As a hypothetical example, a politician who believes that surrender is the way to deal with voracious enemies, or that the citizen should be a ward of the State, just might end up being a little more dangerous than a politician who believes the world was created in seven days.