I've always said that you can't be a Republican and follow the supposed teachings of 'jesus'. The story of jesus has him saying and doing some really jerk things also though, like saying to leave your family and follow him (family values?), and killing a tree that 'he' supposedly made because it wasn't producing fruit during a time when it wasn't supposed to.
2 theories on this that work together:
1. Oligarchs and plutocrats (currently made up mostly of oil money) co-opt religion for power and money. Examples: Bush, Saudi Arabia, etc....
2. People as a whole are not all that smart. Example: Santorum and followers.