"Don't insult other people. You don't like it and neither do they. It starts fights." -- my Mother.

If your opinion is so sacred to you that you cannot civilly defend it, if you must resort to insults, perhaps your opinion isn't as well thought out as you you thought or you simply can't articulate your views well. In either case you should give your thoughts more thought.

(Sometimes I long for the days when an insult would bring an apology or a meeting with swords and/or pistols.)