Atheists and Christians: Why do we have to make things personal?

Why can't we agree to disagree in things, and be civil when debating. Instead many personal attacks ensue, along with feelings of bitterness and hatred. We should want to come to conclusions working together, instead of butting heads and getting nowhere. A little consideration goes a long way in receiving respect from one another. We aren't each others enemies, we are all in this life trying to figure things out.