John, I think you’re on to something. For a Muslim to slaughter American infidels is surely protected under the Religious Freedom Restoration Act of 1993. That Act permits Native Americans to use peyote for religious purposes.
Yes, I see your point. For everyone else peyote is forbidden. For Native Americans it is a protected religious practice.
For everyone else killing someone who offends your faith is forbidden. For Muslims it is a protected religious practice.