If history has shown us anything, it's that unexpected things happen all the time. The issues that politicians debate today will not be the issues they will debate in 4 years. So what elections about, really, but trying to get a feel for the candidate and how they think? Given that it's impossible to know what President Obama or President Romney (shudder...) might be faced with in 4 years, we vote for the man and his worldview.
What is more fundamental to a candidate's worldview than his religion? One's religion influences (or, well, should, at least according to most religious texts I know. More in a future post) one's perception of absolutely everything, so why is it off limits to discuss if Romney believes in magic underwear or if Obama believes in the Immaculate Conception?