content: You give the offending party a chance to rehabilitate, that is the way of our civilized culture.  If they don't, then you remove them in the necessary way, per our laws.  I'd advocate exile for radicals (violent or not).  But, then you'd need a common-sense border protection system in place.    Barring that, I guess we just mix everyone together and hope people assimilate peacefully after a few generations and don't kill too many of eachother to create insurmountable ill will.