Does Islam justify terrorism, and what do groups like ISIS get wrong?

Understanding the question

This question deserves a direct answer, not a defensive one: terrorism carried out in the name of Islam is a real, serious problem that has caused enormous harm — including to Muslims themselves, who make up the majority of victims of groups like ISIS worldwide. Muslims addressing this honestly is more credible than avoiding it.

What mainstream Islamic scholarship says

Major Islamic institutions and scholars across the theological and geographic spectrum — including Al-Azhar University (one of the oldest and most respected centers of Sunni Islamic scholarship), national fatwa councils across the Muslim-majority world, and prominent independent scholars — have issued clear, public condemnations of terrorism and specifically of attacks on civilians, citing the same classical legal tradition discussed on our “Kill Them Wherever You Find Them” page: prohibitions on harming non-combatants, women, children, and religious clergy not engaged in combat.

How groups like ISIS justify their actions

Extremist groups rely on several specific distortions of the Islamic legal tradition:

• Selective quotation — citing verses about fighting (like 2:191, discussed on our dedicated page) while dropping the surrounding restrictions.
• Rejecting the requirement of legitimate authority. Classical Islamic law requires a recognized political/religious authority to formally declare jihad — not private individuals or informal groups. Groups like ISIS declare jihad without this recognized authority, a point mainstream scholars raise directly against their legitimacy.
• Rejecting classical restrictions on who can be targeted. Deliberately targeting civilians, a practice condemned by mainstream Islamic law, is core to groups like ISIS and al-Qaeda’s tactics — this is not a minor technical violation but a direct contradiction of the classical rules of engagement discussed elsewhere on this site.
• Takfir (declaring other Muslims non-Muslim). ISIS in particular has used this to justify violence against Muslims who reject its authority — a practice mainstream Sunni and Shia scholarship treats as one of the gravest theological errors a Muslim can make, given the severity classical scholarship attaches to wrongly excommunicating a fellow Muslim.

Why this matters for ordinary Muslims

The overwhelming majority of Muslims worldwide have no connection to, and actively reject, these groups — global surveys and polling consistently show large majority disapproval of ISIS and similar groups among Muslim populations worldwide, including in Muslim-majority countries most directly affected by their violence. Muslims are, disproportionately, the victims of this violence, not merely bystanders to a Western-versus-Islam narrative these groups themselves try to promote.

Common misunderstanding

Two mistakes are common: assuming Islam as a religion is responsible for the actions of groups that mainstream Islamic scholarship itself rejects as illegitimate; and, in the opposite direction, assuming these groups have no connection to Islamic texts at all. The more accurate picture is that groups like ISIS selectively distort a real legal tradition, while ignoring the restrictions and authority requirements that same tradition places on legitimate warfare.

Conclusion

Mainstream Islamic scholarship, across essentially every major school of thought, condemns terrorism and the deliberate targeting of civilians as violations of Islamic law, not applications of it. Groups like ISIS achieve their stated religious legitimacy only by discarding the very legal restrictions — on authority, on civilian protection, on due process — that classical Islamic jurisprudence built into the concept of legitimate warfare.