We read that terrorists have referred to the those innocent civilians massacred at Tunisia's Bardo museum as "infidels". One horrifying aspect of extremism, be it religious or secular, is that a group’s adherents believe that their particular belief system imbues them with superiority over others, leading them often to regard non-adherents as either a means to an end, or worse, as sub-human enemies worthy of eradication.
Throughout human history people professing all faiths and none have behaved in similarly appalling ways using various justifications. People of nominal Christian faith perpetrated genocide against Muslims in former Yugoslavia; tribal differences were used to fuel genocide in Rwanda; Nazis in Germany used ideological and racial justifications for the holocaust (perpetrated by alleged Christians against Jews and others) and wars of aggression; and communist political ideology was used by people to justify atrocities in Cambodia and by the Soviets.
The best way to defeat terrorism at home or abroad and to confront dictators is to focus relentlessly on human rights, because we each enjoy these by virtue solely of our humanity not as gifts of state or God. Human rights are no panacea, they must be defended, sometimes requiring action and sacrifice by those in safety on behalf of victims.
However, they offer hope not just because they confer the right to speak freely, practice religion, be an atheist and elect governments, but because they remind us that irrespective of any religious, national, tribal, racial, political, ideological or ethnic identity, we are all united in being human and therefore owe one another respect and protection.