"The listener can either choose not to listen, or to criticize the offensive expression." yes this is the way the listener should react. but lets live in the real world where we have radicals and extremists. Logic and rationality is not their thing. They have a strong emotion towards their religion no matter how irrational their religion might be. We already know what these radicals can do. the 9/11 attacks, the london bombings etc. by our freedom of speech we are further fueling these extremists. In other words we are starting the fire ourselves. By our freedom of speech we are giving them a chance to further brain wash the youth by telling them how "evil" the nonbelievers are. so we should indulge in self cenorship.