There's a difference between worshiping Satan and killing people.
The first is legal and the second isn't.
The first is protected by the first ammendendement the second is not.
And you already know that...
You made my point. Not all religious practices are legal (Satanic sacrifices of children). That is the whole point! What many don't take into account is that the Quran and the Hadith advocate killing infidels, and more.