The Pew Forum released a fascinating study that shows American Atheists & Agnostics are better informed about religion than other Americans, including Jews, Mormons, Protestants, Catholics, and others. Executive summary link here.
The Pew Data show we are a nation of ignorant Americans, who don't know other religions, and who don't know much about their own religion either, unless you're an Atheist or Agnostic. Fox News and the Republicans that Rupert Murdoch funds have done an awesome job of spreading mis-information about how persecuted Christianity[TM] is in America.
At least the Atheists and Agnostics are a little better informed than the rest of the Americans that took the quiz - "know your enemy" - Sun Tzu
Take an abbreviated version of the quiz yourself, here. Yeah, I got 15 out of 15. It was very easy - but I've paid attention in grade school, high school, CCD class, I know my US Constitution, and I don't watch Fox News - except for occasional entertainment purposes.