But you're attributing that to being a problem of Islam in and of itself. The vast majority of Muslims are not members of ISIS.
Oh also the Holocaust. Christians did that (although the Nazis had a bit of a weird relationship with the rest of Christianity, much as ISIS does with the rest of Islam).
There's a difference between someone doing something with Islam being their primary motivating factor, and someone who just happens to be Muslim doing something harmful or violent.
I get so tired of people clutching at straws trying to find remotely modern examples of Christian mass-murder and resorting to the KKK and Nazi Germany.
The Klan was a race-based organization. They sought to harm non-whites. If the Klan was acting in the name of Christendom, most of their victims wouldn't have been people who were also Christian and whose religious tenets weren't significantly different. (It wasn't something like Protestants killing/abusing/tormenting Catholics. It was relatively conservative evangelical Protestant white people killing/abusing/tormenting relatively conservative evangelical Protestant black people.)
Nazi Germany's violence, again, was a race-ethnicity-based. The role of Christianity in the Third Reich is mixed. But it's pretty obvious from the way they tried to ape ancient Nordic-Germanic pagan imagery and rituals that they weren't by-the-letter religious fundamentalists. Even the genocidal civil war in Yugoslavia was about ethnicity more than religion.
Notice that with the Islamists, it's the opposite. It's always about religion and nothing but it. The mujahideen in Afghanistan were a pan-ethnic, polyglot movement of Afghans, Arabs, Persians and others working under the banner of Islam. Ethnic, national and linguistic identity had no role. The Islamic State has no interest in pan-Arabism; it welcomes non-Arabs into its ranks and wants to expand its reach beyond the Arabic-speaking world; it, too, is an overtly Islamic movement.
The fact is that there is no comparing the desire of fundamentalist Islamists to unite "the Muslim World" against the collective mass of non-Muslims. No one ever speaks of "the Christian World." To the extent that politicized fundamentalist Christianity exists and has existed, it inevitably gets wrapped up in nationalism of some sort and thus by its nature is always localized and limited in scope. There are no Christians calling for other Christians to detonate bombs in non-Christian cities and countries. I haven't heard about any Buddhists or Hindus flying airplanes into buildings or speaking of global religious holy war.