I think on some level you have to think about "what if's" If I take my point alone I could argue about what would happen if the US banned a religion, what could they ban next? Its human nature to question. At the end of the day though you have to deal with the reality that we live in.
I would agree that you need to punish actions. You cannot ban ideas no matter how extreme because at the end of the day what are you really banning? People are still going to think about crazy shit. Its a lot better to allow jdubs to prance around from door to door or sit at a corner stand selling flowers so that they can be questioned and have their crazy ideas out in the open.