Duke: Thanks. I think the point I always try to make is this: You can debate a point vigorously, while still remaining professional and courteous. I would rather argue with someone that holds beliefs that are the polar opposite of mine, because it forces me to marshal my resources, engage my brain and MAKE MY POINT.
Those that resort to ad hominem or simply shilling an intellectually bankrupt position (whether coming from the right or left), dumb the discourse down and turn away those that would find the discussion and debate engaging and would otherwise participate.
No one likes being told they are an idiot, especially by someone who comes across as overbearing, snide and self-righteous.
Keep it clean, keep it fair and keep it interesting.