Might I offer another way to word this sentiment, because as it stands this is nonsense. I wouldn't vote for someone who professes a belief and then doesn't act on it. IMO it means they're false, fickle, duplicitous, or some other undesirable characteristic. For me, the ideal would be someone who is honest about their beliefs and then does their best to live up to those beliefs once in office.
I think what you guys mean is that if someone professed a strong religious conviction and the intent to follow that conviction in office, you wouldn't vote for them. (shrug) That's your option. That's why we're given a vote.
The problem is, you'll never really know what the true beliefs are for those running for office in the U.S. - especially at the national level. Our pluralistic system forces politicians to make promises to competing factions in order to build a coalition that will elect them.