The most visible actors in the so-con wing of the GOP tend to be the Catholics and evangelical Protestants, because of the sheer numbers. As you point out, there aren't that many Mormons and Orthodox Jews in the total population, and not all of them are Republicans. (Harry Reid, for example, is a Mormon.) The bottom line is that these people represent a healthy chunk of the base vote, and one which McCain has never done much to endear himself to.