This is not the first time this question has occurred to me. For years, I have wondered about this absence of public outrage. When I asked about the murder of Iraqi civilians by Sunni and Shiite gangs, my fellow Muslims dodged my questions: “Why did the United States invade Iraq in the first place?” Yes, the U.S. invasion was a mistake. But why is it so hard to take a stand against the killing of women and children? I never got a straight answer.

To be sure, many Muslims have spoken out against the Islamic State, and some clerics have condemned this gang of terrorists; Qatar-based Islamic scholar Yusuf Qaradawi, for instance, said the Islamic State violates sharia law and declared “null and void” the group’s declaration of a caliphate in Iraq and Syria. But their words merely echoed those of non-Muslims who have called for an end to the violence. Surely we can do better. Don’t Muslims have a responsibility to speak out more loudly than others? We need the world to see anti-Islamic State marchers taking to the streets with the passion that we saw at the Gaza rallies in London and Paris. Mainstream Muslims must express our rejection of extremism in clear terms, while doing whatever we can to stop young people from radicalizing.

The common refrain is: “That’s not Islam.” Of course it isn’t. Muslims know that, but we need to understand that others do not. And here’s the problem: To much of the world, the Islamic State, Nigeria’s Boko Haram and other such groups do represent the Muslim community. Today, say the word “Islam” and few think of the glories of our history and culture. Rather, they picture masked men with knives. And as long as our condemnations remain tepid, we give the impression that we accept the crimes of murderers whose savvy YouTube productions reach far and wide. Like it or not, the Islamic State is winning the public relations war.