This author had an interesting conversation with a young Muslim man, via Twitter, the other day. It came in the wake of the murder—by jihadis—of a Catholic priest in France during a Catholic mass. First off, yes, you are correct to chastise me for engaging on Twitter with someone I do not know, over so fraught a subject. Point taken.

In case you need a refresher, on July 26, 2016, two self-proclaimed ISIS sympathizers stormed into a Catholic church in France, during mass, and slit the throat of an 86-year-old Catholic priest as he knelt before them.

This kind of barbarous and savage attack, in the middle of a church service, in cold blood, of a clergyman of advanced age, is usually the stuff of movies. We are accustomed to seeing movie villains carry out such gruesome and amoral acts. True evil of this sort is rarely ever perpetrated in real life in quite this way. It is generally more nuanced and contextualized. In other words, it is usually more banal, as Hannah Arendt would note. Until recently, that is.

ISIS has perpetrated a number of these types of explicit horrors. The radical Islamic group is as close to evil incarnate as one is likely to see, at least since the disappearance of the Nazi party in Germany, or Pol Pot’s Khmer Rouge in Cambodia. ISIS has beheaded women and children, burned alive and drowned prisoners in cages, thrown gay men off of buildings, and stoned alleged adulterers.

And yet, while trying to converse with this young Muslim man, to try to have a respectful dialogue about the atrocities carried out by ISIS, I was stopped dead in my tracks. We could not even start the conversation properly. You see, his starting point was that ISIS is a Shia-led group, which is not truly Islamic, and thus Islam bears no responsibility for ISIS. Wow.

There are two big lies here, or, at least, two big self-delusions. First, ISIS is not a Shia group. ISIS is a radical Sunni group. Secondly, Shia Muslims are true Muslims, though of a different, smaller sect than the Sunnis. There are Shia terrorist groups, mind you (Hezbollah), but this young man’s insistence that ISIS was a Shia group, and thus, not of Islam, was a lie he had told himself in an attempt to deny that his religion could have produced such evil.

Therein lay a huge problem, and a grave danger.

Now, pretty much every single religion has produced evil men, and will likely do so again in the future. Or, more accurately, evil men have latched on to almost every single religion, and committed evil in its name. Islam is not unique in that respect.

After all, we could go through the litany of sins committed in the name of Jesus, or of Zionism, but that is not the point. The point is that, at this moment in history, radical Islamists are perverting Islam and routinely committing evil acts. Not all Muslims, mind you, or even close to a majority, are complicit in this evil, or approve of it, but some most assuredly are committing evil in the name of Islam, while others approve of the horrors as the “defense” of Islam.

The effect of the accumulation of these attacks on the West is similar to pressure building in a closed container. Whenever an attack occurs in a Western country, or against Westerners, the pressure builds. It might be relieved a bit when Western armies strike back, kill a terrorist leader, or bomb a camp, but the pressure does not completely dissipate.

Another way the pressure is relieved is through the severe, public, and vociferous condemnation of these attacks by other Muslims. When other Muslims come out and repudiate ISIS (as most surely do, even if only in private), Westerners are able to exhale just a small amount, and tell themselves that at some point, this religion will get control of itself, sort itself out, and stop lashing out at the West.

However, when other Muslims deny that radical Sunni Islam is the problem, or when they refuse to even acknowledge that ISIS is a radical Islamic group, that is a recipe to accelerate the pressure build to the point that the West is going to explode.

And notice that I am not even commenting on attacks on the East: India, Bangladesh, Russia, and others. That is a whole other cauldron, bubbling to the point of overflow.

I will be very careful here. The following is not a recommended course of action, nor even a prediction of a forgone conclusion. It is a warning. It is a call for prevention. It is a wake-up call.

The West is on the verge of declaring all-out war on Islam.

Be assured that it will be terrible for everyone across the world. It is a looming danger.

How could it possibly start, you might ask? Surely no country will officially relaunch the Crusades. No, probably not. What may happen, though, is the world stumbles into the New Crusades much as it almost stumbled into nuclear war during the Cuban Missile Crisis, or stumbled into World War I in 1914.

Imagine the rise of a private, non-state-affiliated group, possibly led by former military members from Western nations. Think of private military contractors, finished with their contracts to fight for a sovereign nation, who decide on their own to strike back at mosques and other symbols of Islam across the globe, in retaliation for attacks by al-Qa’ida and ISIS. They are fed up with the seeming ineffectual response of Western governments, and decide to take matters into their own hands.

One of these independent groups, let us say, one perhaps steeped in the symbols of the Crusades and militant Christianity—like the Knights Templar—attacks a site or sites in Mecca or Medina in a spectacular fashion. Many die, and great physical damage is done to the Islamic holy sites. The group publicizes its attack far and wide, and claims it in the name of Christianity. It formally and proudly launches a New Crusade. It names itself. It calls on others to join it, across the world, in attacks on Islam. And it challenges Western nations to join its cause.

Do you see where this might lead? If you think something like this could never happen, you are not a student of history and you fail to recognize exactly where we are in the world today. Never mind how we got here, or the complicity of the West—real or imagined—in antagonizing Muslims in a series of wars across the Middle East. None of that will matter.

All that will matter is that the world will have stumbled into global chaos and religious war. It is not too late to stop it, but it might be soon.