If they even exist, and I would argue they don't (and can't) in a free society, they absolutely cannot be punishable by the state or via corporal sanctions and must exclusively be responded to by, essentially, by pscyhological/social pressures (as churches generally provide). This was the position largely shared by Machiavelli and Thomas Jefferson, as far as I can tell, and while it's more nuanced than most positions on the subject it's not that hard to understand.