Why can't Religious People and Atheists learn to get along with each other?

Who says they can't? I have many atheist friends and colleagues, and I've been invited to address local atheist/freethinker meetings despite my status as a theist. In real life, most theists and atheists can get along quite well. That's because real life isn't like this website, where people are constantly at each other's throats. My spouse was an atheist for many years. If it bothered me that much, would the relationship have continued? But as it happened, our difference of religious opinions was a non-issue.