I'd rather live my own life and enjoy it than spend my life consumed with telling others what to do and how they are wrong because they don't share my worldview.
An "inauthentic" life becomes worse when, if you follow some of the new atheists, you are supposed to spend at least part of it mocking the views of others. Mocking is not a logic argument. Therefore my question is: "Is it far more important to spend the vast majority of your limited time telling others that they are wrong rather than living your own finite life? What is the benefit of such a life both to oneself and to others?" Whatever your answer, it is equally relevant to atheists, theists, agnostics and non-theists.
Of course, the other huge philosophical question is: "What if I am wrong and I have spent the majority of my finite life telling people to follow my error?"