There's method to my madness

I was checking out the background and voting records of the candidates for U.S. Presidential office. It turns out that only the democratic nominees had a voting record, seeing that Bush and Cheney haven't had Senate/Congress membership since before 2000. The site that furnished the voting information also featured background information about the candidates, like their year of birth, family information, and religious affiliation.

I was surprised to learn that thee of the four gentlemen running for the highest offices in the land are affiliated with the SAME religion. What do you suppose that religion might be? Odd man out is here.