I'm not sure the tile isn't a little misleading. If you read on into the article it states: "On questions about Christianity, Mormons scored the highest, with an average of about eight correct answers out of 12, followed by white evangelicals, with an average of just over seven correct answers. Jews, along with atheists and agnostics, knew the most about other faiths......"

So Christians actually knew more about Christianity than atheists and agnostics, they knew less about other religions bringing their OVERALL score under atheists and agnostics. Title and even part of the content is misleading.