I'm pretty sure a candidate admitting to being the Anti-Christ would negate the relevance of the non-christian vote. Either you believe him, which means you believe in Christianity and would be in an odd spot to support him, or you do not believe him, in which case he is a fruitcake and you probably should not be voting for him. 

Unless your are a legit devil-worshiper I suppose. An anti-christ candidate would be right down their ally, but as far as I know devil-worshipers don't have much lobbying power outside of Dick Cheney's circle.