Don't misinterpret what I said.
I really would engage them in a calm rational discussion. As MT said, let'em talk; the stupid shines right on through. We've all seen it here in the O-Club many times.
Sometimes, Funked's imaginary type folks even finally see their own stupidity if you give them the chance. Not often, but it does happen.
However, I've also found that calm, rational discussion can often bring out the worst in those that are unable to form rational thought and carry on a polite debate. Thus, it ofter does move them to violence as they can't express themselves any other way.
So, bearing that in mind, you have to be ready for them to explode on you. And, as I said, you're cleared in hot if you're willing to let them throw the first punch.