This is true of both Catholics and protestants. While one can point to genocides by Muslims in South Asia and in Turkey, one must also acknowledge the Spanish Inquisition (which didn’t end until Napoleon essentially annexed Spain), the Taiping Rebellion (in which a man who claimed to be Jesus’ brother led a rebellion that resulted in 20M deaths), and a plethora of wars and massacres between the Catholics and protestants from the Dark Ages through the Renaissance. Oh, and then there were untold tens of thousands of natives in the Western Hemisphere who fell to the conquistadors (and many hundreds of thousands — perhaps millions — who fell to the smallpox carried ashore by the Europeans).
What’s more, the case can be made that Jews (as opposed to the subset referred to as ‘Zionists’) have been much safer among Muslims than among those who claimed to be Christians. Even today, they are considered a protected minority in Iran — at the order of Ayatollah Khomeini, no less. This doesn’t mean that they haven’t suffered at the hands of Muslims, but even if we completely discount the Holocaust, Jews suffered much more at those who claimed to follow Christ. In fact, the very first Jewish ghetto was opened at the direction of the pope, not far outside Rome.
Full disclaimer: I am a strong Christian. The Church of which I am a member agrees with both Islam and Judaism that only God is God, and that Jesus was not God, but man. We do hold Him to be the only begotten Son of God and is our Savior, but He was still not God, but man only. This also means that we do not believe that either Catholics or protestants are themselves Christian.
For the sake of those who have allowed themselves to be convinced that Islam is a religion of violence, I should note that I’ve walked the streets of Dubai many times, and can attest it is much safer there than in any major American city. I don’t like making that admission, but it is true nonetheless. As is the case with modern-day Catholicism and Protestantism, most violence in modern-day Islam stems less from religious fervor and much more from poverty and political instability.