Ours was an inauspicious first meeting. Nawaz, a former Muslim extremist turned liberal reformer, had just participated in a public debate about the nature of Islam. Though he had spent five years in an Egyptian prison for attempting to restore a medieval “caliphate,” Nawaz argued in favor of the motion that night, affirming that Islam is, indeed, “a religion of peace.” Harris, a well-known atheist and strident critic of Islam, had been in the audience. At a dinner later that evening, Harris was asked to comment on the event. He addressed his remarks directly to Nawaz:

Harris: Maajid, it seems to me that you have a problem. You need to convince the world—especially the Muslim world—that Islam is a religion of peace that has been hijacked by extremists. But the problem is that Islam isn ’ t a religion of peace, and the so-called extremists are seeking to implement what is arguably the most honest reading of the faith’s actual doctrine. So the path of reform appears to be one of pretense: You seem obliged to pretend that the doctrine is something other than it is—for instance, you must pretend that jihad is just an inner spiritual struggle, whereas it’s primarily a doctrine of holy war. Here, in this room, can’t you just be honest with us? Is the path forward for Islam a matter of pretending certain things are true long enough and hard enough so as to make them true?

Nawaz: Are you calling me a liar?

Harris: What?

Nawaz: Are you calling me a liar?

It was good that we weren’t seated at the same table, because we were now more apes than scholars. The conversation ended abruptly, and with bad feelings. Happily, the room quickly erupted with dozens of parallel conversations, diffusing the tension.

Talking about Islam today is a dangerous business. Disagreements about the role this religion plays in the world have become a wellspring of intolerance and violence. Cartoonists have been massacred in Paris to shouts of “We have avenged the Prophet!” Secular bloggers have been hacked to death in Bangladesh. Embassies have burned over YouTube videos. And young men and women by the thousands have abandoned their lives in free societies to join the apocalyptic savagery of ISIS. For years, Western politicians and commentators have struggled to understand this phenomenon. And many have struggled not to understand it, denying any link between “Muslim extremism” and the religion of Islam.

Honest conversation about the need for reform within Islam has become a necessity. So we began our dialogue anew, and initial doubts about each other’s integrity and motives were soon replaced by mutual trust and respect. Neither of us would have imagined having such a productive conversation with the other 10 years ago. The result is now a short book, Islam and the Future of Tolerance.

What most discussions of “Muslim extremism” miss, and what is obfuscated at every turn by commentators like Glenn Greenwald, Reza Aslan, Karen Armstrong—and even Nicholas Kristof and Ben Affleck—is the power of specific religious ideas such as martyrdom, apostasy, blasphemy, prophecy, and honor. These ideas do not represent the totality of Islam, but neither are they foreign to it. Nor do they exist in precisely the same way in other faiths. There is a reason why no one is losing sleep over the threat posed by Jain and Quaker “extremists.” Specific doctrines matter.

Since 9/11, the whole focus of the international community has been on destroying terrorist organizations like al Qaeda and ISIS, as if they were mere criminal gangs that needed to be disrupted operationally. The briefest survey of the state of the world, from North Africa to the North-West Frontier, demonstrates that this strategy has failed, abysmally.

The underlying ideology—we call it “Islamism”—has metastasized and must be confronted directly. After more than a decade of conventional, physical wars, we must finally wage an effective war of ideas.

Islamism, often referred to as “political Islam,” is the desire to impose a version of Islam on the rest of society. Political Islamists, like the Muslim Brotherhood, generally do not believe in resorting to violence, though there are different attitudes even among Brotherhood franchises toward democratic participation, ranging from post-Islamists like the Ennadha Party in Tunisia, to semi-authoritarian conservatives, like South Asia’s Jamat-e-Islami. “Jihadism,” on the other hand, is the use of force to spread Islamism.

Political Islam is an offshoot of religious Islam and draws much of its inspiration from the Quran and the hadith (the sayings of the Prophet Muhammad). To be sure, it does not represent the faith in all its forms, but unless challenged, the underlying problems of religious literalism, dogmatism, and pious intolerance are left untreated and continue to spread. A poll in 2014, published in the Saudi-owned newspaper al-Hayat, found that 92 percent of Saudis believe that ISIS “conforms to the values of Islam and Islamic law.” Clearly, ISIS has something to do with Islam. That something is borne of a literalist reading of specific texts within the canon, a reading that many Saudi-based Salafists (a literalist movement that forms state-sanctioned Islam in Saudi Arabia) and ISIS share:

“And as for the male and female thief, cut off their hands as recompense for what they have earned, an exemplary punishment from Allah; and Allah is Mighty, Wise. ” (al-Qur’an 5:38)

Of course, the Bible contains barbaric passages, as well. But there are historical and theological reasons why Christians and Jews can now easily ignore them. Unfortunately, out of excessive concern not to appear biased, many liberals consider any discussion of the special problem posed by Islamism to be a sign of bigotry. This attitude helps bar the door to reform.

To call ISIS “un-Islamic,” as President Obama has repeatedly done, and as Prime Minister Cameron recently stopped doing, is to play a dangerous game with words. Calling out and combating the ideology of Islamism is the only way that non-Muslims can help those liberal Muslims who wish to reform their faith from within. And failing to do so means abandoning the most vulnerable in Muslim communities—women, gays, apostates, freethinkers, and intellectuals—people like Nobel Peace Prize nominee Raif Badawi, who is being lashed in Saudi Arabia for the “crime” of writing a blog.

We do not entirely agree on how, and how fully, religion should be subjected to criticism in our society, but we both believe that merely repeating platitudes like “Islam is a religion of peace,” despite evidence that many zealots see it as a religion of war, blurs the line between truly peaceful and tolerant Muslims and those who aspire to drag humanity back to the seventh century.

Holding Islam up to scrutiny, rationally and ethically, must not be confused with anti-Muslim bigotry. Cries of “Islamophobia,” which have become ubiquitous on college campuses and in much of the liberal press, have been used to silence legitimate criticism. In an open society, no idea can be above scrutiny, just as no people should be beneath dignity.

We can testify to the power of honest dialogue on these topics. Though we initially met under circumstances that were overtly hostile, we pressed forward with civility and ended in genuine friendship. Without this type of engagement, the only alternative we see is continued intolerance and violence. And we have all seen far too much of that already.