"No, what I am saying is that why do people have to argue each other about their beliefs in the first place if no harm is being done by these beliefs?"
Olivia, it's the "no harm is being done" that probably triggers off a lot of the debating. When people are so sure that their beliefs are true that they are constantly stepping outside of their own boundaries to try to impose them on others, they definitely are doing harm. It may not be physical harm, or even an infringement on civil rights (though we all know religion has been both, and often continues to be), it also inflicts the harm of guilt, shame, making people feel inadequate because they don't accept someone else's "proof" (which is never really any proof at all), etc.
Reading this thread from the beginning, some members of this forum have an irritating (or amusing) smugness about being "right." While this probably doesn't really inflict any harm on those of us who are mentally healthy, it is at best an annoying throwback to outdated religious beliefs, often delivered in an oh-so-holy, condescending manner. It not only invites "debate," it demands it.