The words Islam, Islamism, jihad and jihadism are often thrown together as though they describe the exact same thing. They do not.
Islam is a religion followed by roughly two billion people. Islamism is a broad family of political ideologies that seek a greater role for Islam in government, law or public life. Jihad is an Islamic concept of struggle or striving that has both non-military and military meanings. Jihadism is a modern extremist ideology that turns armed jihad into the centerpiece of a revolutionary political project.
And even within jihadism, there is no single movement.
Al-Qaeda and ISIS became enemies. ISIS considers the Taliban an enemy. Hamas has fought and killed Salafi-jihadists in Gaza. Hezbollah and ISIS fought on opposing sides in Syria. Groups that are routinely placed under the same broad heading can disagree over nationalism, elections, Iran, Shi’a Muslims, Muslim governments, the caliphate and even which Muslims may legitimately be killed.
Understanding jihadist terrorism therefore requires something more useful than asking whether terrorism is “Islamic” or “un-Islamic.”
The important questions are: What do these movements actually believe? How do they justify violence? Where did those ideas come from? How representative are they of Muslims generally? And how different are organizations such as ISIS, al-Qaeda, Hamas, Palestinian Islamic Jihad and Hezbollah?
Islam, Islamism and jihadism are not the same thing
The most important distinction is also the simplest.
Islam is a global monotheistic religion centered on the Quran and the teachings and example of the Prophet Muhammad. Like Christianity and Judaism, it contains multiple schools of law, theology and interpretation.
Islamism is political. The term describes a broad range of movements that believe Islam should have a significant role in government, law or the organization of society.
That category is extremely broad. An Islamist may participate in elections. Another may reject democracy. Another may support revolution. Some Islamist organizations use violence, while others do not.
Calling someone an Islamist therefore does not mean that person supports terrorism.
Jihadism is narrower. It describes a modern militant ideology in which armed jihad becomes an immediate religious and political obligation, often coupled with the belief that existing Muslim governments are illegitimate and that violence is permissible against enemies identified by the movement.
For al-Qaeda and ISIS in particular, specialists frequently use the more precise term Salafi-jihadism.
Salafism itself should not be confused with terrorism. It is a broad Sunni revivalist current whose followers seek to emulate the earliest generations of Muslims. It includes quietist and political currents as well as the much smaller violent Salafi-jihadist current.
That is why phrases such as “Islamic terrorism,” “radical Islam” and “Islamic fundamentalism” often create more confusion than clarity.
For organizations such as al-Qaeda and ISIS, jihadist terrorism or Salafi-jihadist terrorism is generally more precise.
What does jihad actually mean?
“Jihad means holy war” is an oversimplification.
But the opposite claim, that jihad has nothing to do with warfare, is also historically inaccurate.
The Arabic root of jihad conveys striving, struggle or exertion. Islamic tradition has applied the concept in moral, spiritual, social and military contexts.
Classical Islamic jurisprudence also developed an extensive law of armed jihad. Muslim jurists debated when warfare was permissible, who could authorize it, how enemies and prisoners were to be treated, when truces could be made and which people could not be deliberately killed.
A famous hadith recorded in Sahih al-Bukhari, for example, reports that the Prophet Muhammad prohibited the killing of women and children after a woman was found dead during a military expedition.
So the crucial disagreement between jihadists and their Muslim opponents is not simply whether the concept of armed jihad exists.
It plainly does.
The dispute concerns who may declare it, under what circumstances, against whom, and according to which rules.
That distinction is fundamental to understanding modern jihadism.
How modern jihadists changed the idea
Modern jihadism did not emerge fully formed from medieval Islamic law.
Its development involved a long series of reinterpretations, political movements, wars and ideological ruptures.
Twentieth-century Islamist thinkers such as Abul A’la Maududi and Sayyid Qutb helped popularize ideas about divine sovereignty and the corruption of supposedly Muslim societies. Qutb’s concept of modern jahiliyya, invoking the pre-Islamic condition of ignorance to describe contemporary societies, became especially influential among later militants.
But there was no straight line from Qutb to ISIS.
During the Soviet-Afghan war, Palestinian cleric Abdullah Azzam argued that defending Muslim territory could become an individual obligation on Muslims. The Afghan jihad also created international networks linking militants from different countries.
Al-Qaeda subsequently transformed that transnational infrastructure into something more ambitious.
In its February 1998 declaration, Osama bin Laden and his co-signatories announced that killing Americans and their allies, including civilians and military personnel, was an individual duty wherever attacks were possible.
That was a dramatic expansion of the target.
Al-Qaeda’s strategy increasingly emphasized the “far enemy,” particularly the United States, which it blamed for supporting Muslim governments it opposed, stationing forces in the Middle East and supporting Israel.
Then came another rupture.
Abu Musab al-Zarqawi’s movement in Iraq pursued extraordinarily violent sectarian attacks, particularly against Shi’a Muslims. Al-Qaeda’s leadership worried that this strategy was alienating Muslims and undermining its larger project.
The disagreement eventually became an organizational divorce.
In February 2014, al-Qaeda’s General Command formally disavowed ISIS, declaring that it had “no links” or organizational relationship with the group.
The two movements subsequently fought one another.
That fact alone demolishes the idea that jihadism is a single organization with a single hierarchy or universally agreed doctrine.
What do jihadists believe?
Different organizations have different doctrines, but several concepts recur in Salafi-jihadist ideology.
Tawhid, the oneness of God, is a foundational belief shared by Muslims generally. Jihadists give it a radical political application, treating forms of human legislation or political sovereignty as violations of God’s exclusive authority.
Hakimiyya, or divine sovereignty, is used to argue that political systems based on human legislation are illegitimate. Democracy can therefore be portrayed not merely as a bad political system but as a rebellion against God.
Jahiliyya, traditionally associated with the pre-Islamic era, is extended to modern Muslim societies said to have abandoned genuine Islam.
Then comes one of the most consequential concepts: takfir.
Takfir means declaring a professing Muslim to be an unbeliever or apostate.
It matters enormously because jihadist organizations operate overwhelmingly in Muslim societies. If Muslims who work for a government, vote in elections, serve in a security force, belong to another sect or reject the jihadists’ authority can be declared apostates, they can then be reclassified as legitimate targets.
Takfir is therefore one of the mechanisms that allows jihadist movements to turn violence inward against other Muslims.
This is also precisely where major Muslim religious authorities have challenged them.
The Amman Message, developed beginning in 2004 and subsequently endorsed by hundreds of Muslim scholars and major Islamic institutions, recognized multiple Sunni, Shi’a and other Islamic schools and sharply restricted the ability to declare their followers apostates.
That is not a semantic disagreement. It attacks one of the central mechanisms used by extremist movements to legitimize killing other Muslims.
Why do jihadist groups kill civilians?
There is no single justification shared by every organization.
Al-Qaeda’s 1998 declaration explicitly expanded its claimed religious duty to include American civilians as well as military personnel.
Jihadist arguments have also invoked retaliation, collective responsibility, self-defense, support for hostile governments and the reclassification of supposed civilians as participants in a war.
ISIS went further.
In a 2016 article in its propaganda magazine Dabiq, ISIS argued that its hostility toward Western societies was not merely a reaction to military intervention or foreign policy. It explicitly placed religious disbelief itself among the reasons for its hostility and said that hostility would remain even if political grievances disappeared.
This distinction matters because explanations of jihadist violence sometimes fall into two equally simplistic camps.
One says the violence is purely theological.
The other says religion is irrelevant and jihadist violence is simply a reaction to Western policy, poverty or occupation.
The evidence supports neither monocausal explanation.
Religion, war, political grievances, social networks, identity, state collapse, revenge and individual circumstances can interact in different ways in different conflicts.
The movements themselves also disagree about which of these factors should matter most.
How Muslim scholars have answered ISIS
Muslim opposition to jihadist violence is sometimes described simply as condemnation. But some of the most important responses have been detailed legal and theological arguments.
One major example came in September 2014, when more than 120 Muslim scholars and religious authorities issued an Open Letter to ISIS leader Abu Bakr al-Baghdadi.
Rather than arguing that ISIS had nothing whatsoever to do with Islamic texts, the scholars challenged the organization on its own claimed religious ground.
Among other things, they argued that religious rulings could not be issued without the necessary qualifications, that Quranic passages could not legitimately be cherry-picked without considering the Quran and hadith as a whole, that killing innocent people was forbidden, that forced conversion and torture were forbidden, and that a caliphate could not simply be declared without the required Muslim consensus.
They also rejected ISIS’s revival of slavery.
The Amman Message similarly attacked indiscriminate takfir and unauthorized religious rulings.
The 2016 Marrakesh Declaration approached another issue: the treatment of religious minorities in Muslim-majority societies. Muslim scholars and leaders involved in the declaration invoked the Charter of Medina as a basis for citizenship and religious rights and explicitly condemned using religion to violate the rights of minorities.
These initiatives do not prove that Muslim institutions have eliminated extremist ideology. They plainly have not. Nor does issuing a declaration demonstrate that it changes militants’ behavior.
But they show something important: the dispute with jihadism exists inside Islamic jurisprudence and theology, not merely between Islam and the outside world.
What about suicide bombing?
Islamic canonical texts contain extremely strong prohibitions on suicide.
Sahih al-Bukhari and Sahih Muslim include traditions warning of severe punishment for those who intentionally kill themselves. Shi’a tradition likewise contains condemnations of suicide.
Modern jihadist and other militant organizations have attempted to circumvent that prohibition by distinguishing suicide from what they call “martyrdom operations.”
That distinction has itself been fiercely disputed.
Saudi Arabia’s former Grand Mufti Abd al-Aziz Ibn Baz rejected suicide attacks as outside legitimate jihad. Grand Mufti Abd al-Aziz al-Sheikh similarly described suicide bombings as illegitimate and another form of killing oneself.
There is, however, an important complication, particularly for an Israeli audience.
Muslim religious opinion was not universally opposed to suicide attacks against Israelis. Influential cleric Yusuf al-Qaradawi defended Palestinian “martyrdom operations,” and other religious authorities who condemned attacks such as 9/11 drew different conclusions in the Israeli-Palestinian context.
Pretending that this disagreement never existed would give a misleading picture of the theological debate.
Are jihadist ideas representative of Muslims?
No serious analysis can infer the beliefs of roughly two billion Muslims from the ideology of organizations such as ISIS.
But the best evidence also requires dates and caveats.
In Pew Research Center polling published in 2015, ISIS was viewed negatively by overwhelming majorities across the Muslim populations surveyed. In none of the 11 countries included did favorable views of ISIS exceed 15 percent.
Earlier Pew research published in 2013 found a median of roughly seven in ten Muslims across the countries surveyed saying suicide bombing and other violence against civilians in defense of Islam could never be justified.
There were important exceptions. Support for such violence was substantially higher in some conflict-affected populations.
These are historical polling results, not measurements of Muslim opinion in 2026. Comparable current global polling is limited, so they should not be presented as though they describe attitudes today.
Another useful sense of scale comes from the Islamic State’s foreign recruitment.
Researchers at King’s College London’s International Centre for the Study of Radicalisation identified 41,490 international citizens from 80 countries who became affiliated with ISIS in Iraq and Syria between April 2013 and June 2018. The dataset included fighters as well as women and minors.
Against a global Muslim population of roughly 1.9 billion, 41,490 people would amount to about 0.002 percent.
That calculation does not measure everyone who sympathized with ISIS, nor does it measure domestic recruits inside Iraq and Syria. But it illustrates the enormous difference between a transnational extremist movement and the global Muslim population from which it attempted to recruit.
Most victims of jihadist violence are Muslims
One of the most persistent misconceptions about jihadist terrorism is that it is primarily a campaign against Westerners, Christians or Jews.
Its rhetoric often focuses heavily on those enemies.
Its actual violence is concentrated overwhelmingly elsewhere.
The contemporary centers of jihadist activity are countries such as Pakistan and parts of the Sahel, West Africa, the Lake Chad Basin, Somalia, Afghanistan, Syria and other conflict-affected areas.
The Global Terrorism Index 2026, which measures events during 2025, recorded 5,582 terrorism deaths worldwide across 2,944 attacks. The report covers terrorism of all ideologies, not jihadism alone, so those numbers should not be presented as a count of jihadist violence.
Nevertheless, its geography is revealing. Many of the countries most heavily affected by terrorism are Muslim-majority countries or contain very large Muslim populations.
This is not accidental.
Jihadist organizations spend enormous amounts of their energy fighting Muslim governments, Muslim security forces, rival Islamist movements, rival jihadists, Shi’a communities, Sufis and ordinary Sunni Muslims they accuse of collaboration or apostasy.
The theological importance of takfir becomes much clearer once this is understood.
Hamas is not ISIS, and ISIS is not al-Qaeda
The differences among armed Islamist organizations are not academic trivia.
They have produced actual wars.
Hamas offers a particularly important example.
Hamas emerged from the Palestinian Muslim Brotherhood during the First Intifada. Its 1988 Covenant explicitly identified the movement with the Muslim Brotherhood, framed the conflict in religious terms and contained unmistakably antisemitic material, including conspiracy theories and a reference to the Protocols of the Elders of Zion.
In 2017, Hamas issued a new policy document with substantially different language. It defined itself as a “Palestinian Islamic national liberation and resistance movement” and stated that its conflict was with Zionism rather than Jews because of their religion.
The significance of that change remains disputed.
The 2017 document removed much of the overtly antisemitic language of 1988 but did not constitute an established formal repudiation of the older Covenant. It also did not recognize Israel.
Hamas is therefore best understood as an Islamist-nationalist Palestinian movement, not as a Salafi-jihadist organization like ISIS.
The distinction became violently concrete in Gaza.
In August 2009, a Salafi-jihadist group called Jund Ansar Allah declared an “Islamic Emirate” in Rafah and denounced Hamas for failing to impose what it regarded as proper Islamic rule.
Hamas attacked it.
The resulting fighting around the Ibn Taymiyyah Mosque killed at least 24 and possibly as many as 28 people, according to differing contemporary accounts, and effectively destroyed the group. ISIS later cited Hamas’s destruction of the mosque among its criticisms of Hamas.
There are other profound differences.
Hamas has participated in Palestinian elections. ISIS and al-Qaeda reject democratic elections as illegitimate.
Hamas is Palestinian nationalist. ISIS rejects nationalism in favor of a transnational caliphate.
Hamas has received extensive support from Shi’a Iran. Salafi-jihadist organizations such as ISIS are violently anti-Shi’a and have repeatedly massacred Shi’a civilians.
None of this makes Hamas nonviolent or erases its deliberate attacks on civilians, suicide bombings, hostage-taking or the atrocities of October 7, 2023.
It means that terrorist tactics do not make two organizations ideologically identical.
Palestinian Islamic Jihad is different again
Palestinian Islamic Jihad, or PIJ, is also an Islamist Palestinian armed movement, but it developed separately from Hamas.
PIJ made armed struggle more central to its identity from the beginning and was strongly influenced by the Iranian Revolution despite being a Sunni organization.
Unlike Hamas, it has not built the same combination of mass political organization, social institutions and electoral participation.
Its focus remains overwhelmingly Palestinian and anti-Israel rather than the worldwide revolutionary project associated with al-Qaeda or ISIS.
Again, overlapping tactics and religious language should not be confused with identical ideology.
Hezbollah belongs to another tradition
Hezbollah demonstrates why the category becomes even more complicated.
It is a Shi’a Islamist organization created in Lebanon in the context of the early 1980s, with major Iranian Revolutionary Guard involvement and a political theology influenced by Ayatollah Ruhollah Khomeini.
That places Hezbollah in a very different doctrinal tradition from Sunni Salafi-jihadism.
Hezbollah has operated simultaneously as an armed organization, political party and social institution within Lebanon. Its relationship with Iran is also substantially more institutionalized than Hamas’s historically fluctuating relationship with Tehran.
Most obviously, Hezbollah and Sunni jihadists have been enemies on the battlefield.
Hezbollah fought in Syria on behalf of Bashar al-Assad’s government while ISIS and other Sunni jihadist organizations fought against it.
Putting Hezbollah and ISIS into one ideological bucket because both invoke Islam and use political violence obscures more than it explains.
Jihadist movements also fight each other
Perhaps the easiest way to understand the diversity is to look at the bloodshed inside the extremist world itself.
Al-Qaeda formally disowned ISIS.
ISIS and al-Qaeda affiliates fought each other in Syria.
ISIS-K has fought the Taliban.
In Nigeria and the Lake Chad region, the Islamic State West Africa Province split from Abubakar Shekau’s faction of Boko Haram in part over Shekau’s extraordinarily broad use of takfir and his treatment of Muslim civilians.
Hamas crushed a Salafi-jihadist challenge in Gaza.
ISIS has denounced Hamas.
Hezbollah fought ISIS.
These are not minor disagreements between branches of a single movement. They concern fundamental questions: Who is a Muslim? Who has legitimate authority? Can Muslims participate in elections? Is nationalism legitimate? Is cooperation with Shi’a Iran permissible? Who may be killed? Who may declare jihad? And who, if anyone, has the right to proclaim a caliphate?
Why do people join jihadist organizations?
There is no profile that explains every recruit.
Poverty is an especially poor universal explanation.
Research using leaked ISIS personnel records found foreign recruits were often relatively well educated and economically better off than simplistic stereotypes suggested. Some of those seeking suicide roles were among the more privileged recruits.
That does not mean economic conditions are irrelevant.
There is an important distinction between why an individual joins and why a country becomes fertile territory for armed organizations.
War, collapsing government institutions, corruption, sectarian conflict, displacement and weak security can create environments in which extremist groups expand. Personal recruitment may then depend on entirely different factors: family and friendship networks, identity, status, ideology, adventure, revenge, belonging or local grievances.
Research on jihadist networks has repeatedly emphasized the importance of existing social relationships.
People do not necessarily encounter an ideology in isolation and then mechanically become terrorists. Friends, relatives, prisons, armed conflicts and local networks can matter enormously.
Even the familiar term “radicalization” can mislead if it suggests that there is one predictable staircase from conservative religious belief to terrorism.
There isn’t.
The jihadist threat has moved
The fall of ISIS’s territorial “caliphate” in 2019 did not eliminate jihadism.
It changed its geography.
The United Nations’ assessments in 2026 describe an increasingly decentralized Islamic State network, with Africa becoming particularly important to the movement.
ISIS and al-Qaeda affiliates now operate across parts of the Sahel, West Africa, Somalia, Afghanistan and elsewhere, while the threat in Iraq has fallen dramatically from the heights of the Islamic State insurgency.
Pakistan has also experienced a major terrorism resurgence involving Tehrik-e-Taliban Pakistan and other armed groups.
At the same time, the threat to Western countries increasingly includes small cells and individuals influenced online rather than militants receiving detailed instructions from a centralized foreign command.
Propaganda has evolved with the internet: from professionally produced videos and web forums to social media, encrypted platforms and increasingly decentralized digital ecosystems.
The result is a movement that can lose territory without disappearing.
So what is jihadist terrorism?
Jihadist terrorism is best understood as terrorism carried out by modern extremist movements that claim Islamic religious authority for revolutionary armed struggle.
Those movements draw selectively from Islamic scripture, classical legal concepts and modern Islamist thinkers. Their connection to Islamic intellectual history is real.
But saying that does not make their interpretation representative of Islam.
Major Muslim scholars and institutions have challenged jihadist doctrines using the same Islamic textual and legal tradition the extremists claim to represent. They dispute the jihadists’ authority to issue rulings, their use of takfir, their treatment of civilians, their declarations of jihad, their use of suicide attacks and, in ISIS’s case, their claim to have restored a legitimate caliphate.
At the same time, the extremist world is deeply fragmented.
Al-Qaeda is not ISIS. Hamas is not al-Qaeda. Palestinian Islamic Jihad is not Hamas. Hezbollah belongs to a different Shi’a Islamist tradition. Even organizations that agree that violence is legitimate can disagree violently over almost everything else.
That is why terminology matters.
Calling all of this “Islamic terrorism” tells the reader almost nothing about which ideology, organization or conflict is actually being discussed.
Calling every Islamist a jihadist is equally misleading.
And pretending that jihadist ideology has no relationship whatsoever to Islamic history makes it impossible to understand the arguments jihadists themselves make or the Islamic arguments used against them.
The more accurate conclusion is less convenient but far more useful:
Jihadism is a modern extremist interpretation built from real Islamic concepts, radically reworked into a revolutionary ideology of violence. It represents neither Islam as a whole nor a single unified movement. And today, as throughout much of its history, many of the people it kills, fights and declares enemies are Muslims themselves.
