Since Jimmy Carter, religious fundamentalists play a major role in elections. He was the first president who made a point of exhibiting himself as a born again Christian. That sparked a little light in the minds of political campaign managers: Pretend to be a religious fanatic and you can pick up a third of the vote right away. Nobody asked whether Lyndon Johnson went to church every day. Bill Clinton is probably about as religious as I am, meaning zero, but his managers made a point of making sure that every Sunday morning he was in the Baptist church singing hymns.
It's easy to see why conservatives would be salivating at the thought of a Hillary primary challenge. Presidents who face serious primary challenges—Ford, Carter, Bush I—almost always lose. The last president who lost reelection without a serious primary challenge, by contrast, was Herbert Hoover. But in truth, the chances that Obama will face a primary challenge are vanishingly slim, and the chances that he will lose reelection only slightly higher. No wonder conservatives are fantasizing about Hillary Clinton taking down Barack Obama. If she doesn't, it's unlikely they will.