The Constitution doesn't protect anything. The Constitution's purpose is to define the limitations of government, not define the limitations of the people or their religions.
Human sacrifice and suicide bombing can be banned because these things violate the inalienable rights of other individuals; but the religious motives behind human sacrifice and suicide bombing cannot be banned. You cannot stop someone from believing.
The problem isn't in their belief anyway. It's when there are actions.
You can at best say that a mullah's calls for jihad are incitement to riot, kind of the grandaddy of the old "yelling fire" in a crowded movie theater cases.
However, not all muslims issue calls for Holy War, and certainly, most never heed them. You have to go after the folks who issue those fatwas (calls for holy war) for that, not after the believers who might hear them. Neither believing nor hearing is a crime.
You are free to worship Quetzalcoatl if you like; but there are consequences when your beliefs spill over onto other people and you take action by cutting out someone's heart and presenting it to your god. That's defined as murder.
But in that case, YOU pay for it, because you did it, not other followers of Quetzalcoatl.