Actually, six words: I don't want to do it.
Unfortunately, personalities beyond my control have forced me into it.
I don't mind people posting to disagree with me. In fact, I welcome the chance at conversation. However, I have no interest in abusive posters who, after repeated requested to stay away, continue to comment using foul language, attacking not only me but other posters they disagree with.
In summary: I'm not banning anyone from posting. I am banning comments with foul language, insults or those which serve no meaningful purpose to the relevant post. (I might make an exception for SJ, I have a soft spot for the guy)