Having lived in Ohio, the far right is exactly the same as the far left here in San Francisco. What is funny is they do not realize this. So I think its more a personality type selection than actual thought process or belief.
The result of believing the other side is evil, is no one is willing to work together so we all lose.
I think this could be a function of things we've built on the internet such as the ability to "hide" or "block" - even moderators are bad I, an elected DNC delegate is banned from the DailyKos because I disagreed with the Democrats proxy war policy on Syria.
We are in trouble.