Negligence and a lack of attention allowed Al-Qaeda to flourish and attack US soil on September 11, 2001. That event marked the beginning of the “War on Terror.”

A new era of that war is about to begin, following the news of the execution of American journalist James Foley by the Islamic State of Iraq and Syria (ISIS). This act signals that similar crimes by the organization are in the pipeline. It is also likely to have awakened concerned parties to the present danger—Western states as well as regional ones, since they are also threatened by the organization and its sympathizers.

The past 13 years have witnessed some of the largest campaigns against insurgent groups in history. These actions have included military confrontation, offering financial rewards, freezing bank accounts, shutting down propaganda-disseminating media outlets, and killing or detaining many of the organization’s leaders. Despite all that, the War on Terror has been a failure, and the group’s ideology continues to flourish.

So, our enemy is not Al-Qaeda, or ISIS, or the Al-Nusra Front, but their ideologies—concepts which are a source of inspiration and energy. This is the reason why Abu Bakr Al-Baghdadi emerged as the leader of ISIS, just as the late Osama Bin Laden emerged as the leader of Al-Qaeda.

This ideology is also the reason why thousands of youths have arrived in Syria and Iraq ready and willing to die.

Our war—the world’s war, that of Muslims and others—is against evil ideas. Al-Qaeda is an idea, and so is ISIS. It is not about building an army, or expanding on the map or gaining oil fields. It is about a “sacred” group that rules in the name of God, and claims to get closer to Him by offering human sacrifices.

Even if US troops, or Iraqi troops, or Iraqi tribes, kill Baghdadi and his rival, Al-Nusra Front leader Mohammad Al-Golani , and the thousands of terrorists who follow them, the rebirth of Al-Qaeda under a new slogan is almost inevitable.

We are locked in a struggle with extremism—a struggle that hasn’t ended since Ayatollah Ruhollah Khomeini took over power in Iran and since Salafist militant Juhayman Al-Otaybi occupied the Grand Mosque in Mecca in 1979.

Extremism is a disease that plagues the Arab world, many Muslim countries, and minority Muslim societies in European countries, even China. It is an Ebola-like disease—meaning it is not enough to get rid of the patients; you must also fight the virus.

ISIS, and Al-Qaeda before it, should not be seen only as a threat to the West and the followers of other religions, because most of its victims are Muslims, and most of those are Sunni Muslims. Therefore, the biggest burden in the new round of the War on Terror is on Muslim countries, their governments and their intellectuals.

I am certain that this strand of religious extremism will end, and will not be reborn for another 100 years if its sources of funding and its allies in the media and the education system are removed. However, the Islamic world still refuses to fully admit to the extent of the problem of extremism that lies within it. On the one hand, it fights against extremism in the security sphere. On the other hand, it tries to shift the blame onto others instead of admitting its illness and the need for long and harsh treatment.

The virus of extremism has infiltrated society and culture. It is due to this virus that many act like brainwashed people, and roam the streets of their cities repeating the same ideas and defending extremism, more than willing to spread its teachings. And so, whenever counterterrorism forces kill 100 of them, 1,000 more are born.