In the wake of the attacks in Paris this past weekend, statements such as “It doesn’t matter what religion the attackers were,” “Those terrorists weren’t Muslim” and “Terrorism knows no religion” seem commonplace. These statements are frustrating to read, because in this case the religion of the attackers does matter and failure to realize this is a grave mistake on the part of anyone who wants to see ISIS destroyed.

ISIS is an Islamic organization, and it’s important that we don’t run from that reality. While the perverted form of Islam practiced by these terrorists is vastly different than the practices of the other 99.9 percent of Muslims, it is a form of Islam nonetheless. When people claim ISIS and other Islamic terrorist groups are not Islamic, they refuse to consider the impact of religious ideology on ISIS’s behavior. It is to our great disadvantage not to try to understand this group fully.

ISIS has (what it claims to be) religious justification for its tactics, goals and purpose as an organization. In its incredibly selective interpretation of Islamic religious texts such as the Quran and Hadith, we can find explanations for how the group behaves. In the same way detectives look for the motive of a murderer or rapist, we need to look to the ideology of terrorists to understand why they do what they do, and more importantly, how they can be stopped.

It seems the fear of reprisal against non-extremist Muslims is a driving factor behind the claim that these terrorists are not Muslim, and the concern Muslims have regarding reprisal attacks is well warranted. To be clear, there is a bright and clear line between understanding that ISIS is an Islamic organization and believing Muslims are a violent or dangerous group of people. The vast majority of Muslims practice a religion that values peace, cooperation and harmony.

Knowing that Islam is practiced peacefully by virtually every Muslim except those in ISIS, what makes ISIS’s form of Islam so radical and terrible? ISIS takes a very selective and extremist approach to the religious texts of Islam. ISIS and similar groups are part of a distinct movement in Sunni Islamic political thought called “Jihadi-Salafism,” described by Princeton University doctoral candidate Cole Bunzel as having “developed over the course of the later 20th century, combining elements of radical Muslim Brotherhood activism with aspects of the purist Salafi tradition predominant in Saudi Arabia.”

The leadership of ISIS, particularly its so-called Caliph Abu Bakr al-Baghdadi — who holds a master’s degree in Islamic studies — regards itself very highly in the self-proclaimed role as the true bearer of the Salafi tradition. The group’s emphasis on dissociating from “unbelievers” and waging jihad against “heretics” — particularly Shia Muslims, who have been killed at far higher numbers than any group by ISIS — are manifested in its horrific methods of execution and the treatment of religious minorities such as the Yazidis and Christians.

While there are many examples of how ISIS uses its selective interpretation of religious texts to justify its actions, I’ll point to one that is especially illustrative: the “Document of Security” for the Christians of Raqqa. ISIS models its laws for Christians on the seventh-century “Pact of Umar,” which laid out the actions prohibited for Christians living in the Islamic Empire, but with interesting additions that exemplify their extremist ideology.

First, nearly every Muslim would reject the Pact of Umar for their Christian neighbors, as many of the regulations, such as the inability to build places of worship or publicly carry religious texts, violate the commonly held ideal of religious freedom, and just as importantly, modern Islamic legal thought on the rights of non-Muslims.

As scholars such as Yale’s Andrew March argue, additional regulations imposed by the Islamic State in its “Document of Security” demonstrate its extreme ideology. Requirements to turn over officials sought by the ISIS judiciary, to comply with any commands on public modesty and morality and the specification of a jizya, a special tax on Christians, are all ISIS add-ons to the traditional text.

A second very important illustration of ISIS’s theology comes from the importance the group places on truly running itself as an Islamic State. With the exception of the Paris attacks, ISIS hasn’t acted on attacking Western cities, rather focusing its resources on conquering territories in Iraq and Syria and establishing governance. This is contrasted with groups such as al-Qaida, which spent a vast majority of its time and money constructing plots to harm the West. Why does ISIS call itself the “Islamic State” and try to govern a territory when al-Qaida really doesn’t? The answer again is in ISIS’s interpretation of Islamic religious texts.

Al-Baghdadi and other Jihadi-Salafist Muslims view the establishment of a truly Islamic empire, called a caliphate, as a holy and necessary part of Islam. In such a caliphate, Sharia law is enforced strictly and fully, in ways that Muslims in no other country support. This is why we see ISIS enslaving non-Sunni women and children and the gruesome execution videos. The publication of these videos, showing death by burning, stoning and beheading, are not just for ugly entertainment; they serve as proof to ISIS followers that this organization is committed to even the most inhumane parts of Sharia law.

The acquisition and governance of territory is therefore a top objective of the organization because it is the source of its legitimacy as an Islamic State. ISIS has been able to recruit and obtain foreign fighters from countries around the world precisely for this reason. Its control of territory provides ideological merit in the eyes of those who interpret Islamic texts in the same way.

These two examples of ISIS’s textual interpretation in practice lead to some important ways we can bring about its demise. First, publicly challenging ISIS’s interpretation of Islamic texts, which many Muslim scholars already do, can help poke holes in the theology of the organization and reduce its ideological legitimacy in the eyes of potential recruits. Second, the ability to take ISIS’s territory away from it will destroy its status as a true caliphate and render it illegitimate, even by its own principles.

We can’t beat our enemy if we choose to ignore its motives and ideology. The temptation to say ISIS isn’t Islamic is harmful in that it limits our ability to understand what it is and how we can beat it. As we’ve seen, this group is a danger to the Western world and absolutely barbaric to its fellow Muslims in the Middle East, and it does this through its selective and extreme interpretation of Islamic religious texts. We can only come up with a strategy to defeat ISIS once we take it upon ourselves to explore its motivations and justifications for its actions. We can only destroy it once we understand it.