I'm confused about the American Republican party

[kandrathe]

Are there really a subset of American voters that will only vote Republican solely because of religion?

Yes. But, ALL the candidates tend to pander. It's like a mom, apple pie, baseball thing. You gotta love these things or you're just not candidate material. If they go too far, then there are a bunch of people who retreat because they don't want a theocracy.

I never followed the Democrat primaries in the past, are they the same?

How about;

"Secularists are wrong when they ask believers to leave their religion at the door before entering into the public square. Frederick Douglas, Abraham Lincoln, Williams Jennings Bryant, Dorothy Day, Martin Luther King - indeed, the majority of great reformers in American history - were not only motivated by faith, but repeatedly used religious language to argue for their cause. So to say that men and women should not inject their "personal morality" into public policy debates is a practical absurdity. Our law is by definition a codification of morality, much of it grounded in the Judeo-Christian tradition." BARACK OBAMA, Jun. 28, 2006

Democrats are especially sensitive to the Southern Black church and the northern working class Catholic vote, which also garners a significant population of hispanics. In the "bible belt" down south, the Church is your community.