Why is mankind so haughty?

Why is it that, no matter how many judgment calls we call wrong, how many mistakes we make and how many people we offend (as individuals), we never seem to be willing to be humble when it comes to religion? I am fully aware that most religions teach that they are THE ONLY avenue to a better life, heaven, the afterlife, etc. But, as imperfect humans, why is it that we cannot just say, "THESE are MY beliefs." And, recognizing our own individual imperfections, realize that no one person KNOWS (has undeniable proof) the answers to life's big questions, and therefore it may not be the best idea to beat people over the head with their own personal TRUTH?