“Biased” Christian Views?

From the book, The Reason For God by Tim Keller, published by Penguin Group. Why do we Christians seem so narrow and opinionated on public policy issues while others can seem so open-minded? Or is that an illusion? Hear how the views of relativists, agnostics, and atheists are narrow, unprovable, and faith-based. And weigh in more confidently with your convictions!