After the end of the Cold War, religion has once again come to occupy a central place in the study of conflict ( Basedau et al., 2016 ; Fox, 2013 ; Svensson, 2012 ; Toft, 2007 ). In this article, using new data on religious affiliations and more comprehensive data on conflict, we assess first how many of the civil wars after World War II have occurred in countries with different dominant religions. We then find a strong increase in the relative rather than the absolute incidence of conflicts involving Muslim countries and Islamist insurgent movements. Finally, we discuss a range of possible explanations for this pattern.

In 2012, there were six armed conflicts with more than 1000 battle deaths. All of them took place within Muslim countries—in Afghanistan, Pakistan, Sudan, Somalia, Syria, and Yemen. Of the nine rebel groups in these conflicts, seven had an Islamist ideology. We show in this article that 2012 was an extreme year, but not a wide outlier. Are Muslim countries more war-prone or even more prone to violence in general?

In the final column of Table 1 we look at the fraction of independent years in which countries in each group have experienced civil war. Countries with Buddhism and Hinduism are most at risk overall and countries with Folk religion are tied for third place. But these three groups are small (eight, three, and three countries, respectively), and as we will show they suffer comparatively few battle deaths, so they count relatively little in the global pattern of conflict. Among the two largest groups, Muslim countries have a fraction of conflict years (7%) over twice that of Christian countries (3%). This pattern generally persists when we restrict the focus to conflict behavior after the end of the Cold War.

Table 1 shows the absolute and relative incidence of intrastate armed conflict after World War II in countries with different majority religions. Only Islam and Christianity are majority religions in a large number of countries. Out of 49 Muslim countries, 20 (41%) have experienced civil war and 30 out of 110 Christian countries (27%). Since Christian countries are more numerous, they dominate the global pattern of conflict for the period, even though Muslim countries are relatively more prone to conflict. 1

We use a definition of civil war from the Uppsala Conflict Data Program (UCDP): A contested incompatibility over government or territory between the government and one or more opposition movements resulting in at least 25 battle-related deaths in a calendar year. A civil war is an intrastate conflict with more than 1000 battle deaths in a calendar year ( Gleditsch et al., 2002 ).

We use data on religious belonging from a report by the Pew Research Center ( Pew, 2012 ). The study is based on self-identification and does not report on the degree of religious practice. It seeks to assess the number of people who view themselves as belonging to a religious group, including Christianity, Islam, Buddhism, Hinduism, Judaism, and Folk religion. Based on these data, we code a country as “Christian” if a majority of its population identify with that religion. We assume that the majority religion is unchanged for the period 1946–2014, although the exact percentage belonging to a given religion is likely to vary over time. Our detailed data on the majority religion for each country can be found in the online Supplementary Material.

Muslim insurgents are not necessarily motivated by religion. We label as Islamist insurgents those groups that adhere to a religious ideology with the overall goal to strengthen Islam nationally or globally and who are willing and able to use violent means to attain this end ( Mozaffari, 2007 ). In the online supplementary material we provide a complete list of all insurgent groups in internal armed conflicts, with 70 groups marked as Islamist.

No less than 474 insurgent organizations are recorded in the dataset for the period 1946–2014. Many of them originate in, and identify with, ethnic or religious minorities. Although precise data are lacking, it appears that more than 200 insurgent groups consist mainly of Muslims. Many of these operate in countries where Islam is not the majority religion (as in India and the Philippines), but a larger number are active in Muslim countries. There are few non-Muslim insurgent movements in Muslim countries – the movement in Sudan that fought for the independence of South Sudan, and eventually succeeded, is one of the best-known cases.

In what follows, we focus on conflicts involving Muslim countries and Islamist rebel groups. Figure 1 identifies the Muslim countries on the basis of the data cited in Table 1 . All the civil wars for the period 2011–14 have been plotted on the map at the center of the conflict. The map gives a visual impression of a preponderance of civil wars in Muslim countries, although smaller conflicts also occur in other conflict areas, notably in Central and South America, in Sub-Saharan Africa, and in Southeast Asia. Several smaller conflicts are located on the fringe of the Muslim-majority world, for example in the Caucasus, India, and the Philippines. 2 The civil war in Nigeria takes place in the northern and Muslim part of the country between the government and the Islamist group Boko Haram.

Looking at the last 50 years, we do not find a sharp increase in the number of civil wars involving Muslim countries; but since the overall number of civil wars decreased by about one-half after the end of the Cold War, the fraction of conflicts in Muslim countries has increased markedly, as shown in Figure 3 . The increase is particularly dramatic after 9/11. As noted, all civil wars in 2012 took place in Muslim countries, and they all involved Islamist insurgents. The same was the case in 2011. For 2014 the fraction of conflicts occurring in Muslim countries was lower (60%), but still way above the fraction of the world’s countries that have a Muslim majority, or the Muslim fraction of world population (both 23%).

The curve for civil wars in Muslim countries shows a more modest increase during the Cold War than for the world as a whole, it peaks in the early 1990s, then decreases markedly, and finally increases again after 2001. The curve for Islamist insurgencies has also risen rapidly since 2001. In fact, in the most recent years, almost all civil wars have taken place in Muslim countries and most civil wars involve Islamist insurgencies.

In Figure 2 we plot year by year the total number of civil wars as well as the number of civil wars in Muslim countries, and civil wars involving Islamist insurgencies, most of which (but not all) occur in Muslim-majority countries. The top curve shows the familiar increase in civil wars during the Cold War and a little beyond, the sharp decline afterwards, the leveling out in the last decade, and the sudden uptick in 2014.

The riddle of Muslim conflicts

Conflicts in a Muslim country or involving Islamists in opposition have become an increasingly important part of the overall global map of conflict. This is not mainly because the absolute number of such conflicts has risen. In fact, during most of the Cold War the number of conflicts in Muslim countries rose more slowly than the general trend.

The rise in armed conflict during the Cold War in part reflects the strongly increasing number of independent countries, and this applies to Muslim countries, too, but not quite to the same extent. After the end of the Cold War, the number of conflicts in Muslim countries first took a dip, and then increased again, producing essentially a flat trend for the whole period. Islamist conflicts have clearly risen since 2001, well beyond the level they occupied at the end of the Cold War.

Increasingly, the victims of conflict are now found in Muslim countries. There is great and understandable concern about Islamist (or counter-Islamist) terrorism in many Western countries, but the bulk of the battle-related deaths are found in conflicts in Muslim countries, as shown in Figure 4. The figure includes combatants as well as civilian victims.

While the world as a whole is becoming more peaceful, as argued by Mack (2011), Pinker (2011), Goldstein (2011), and scholars at PRIO and Uppsala University (Gleditsch et al., 2016), the Muslim world is not. Thus, the map of global conflict is increasingly colored by civil wars in Muslim countries and also by Islamist insurgencies.

The Islamization of conflicts in Muslim countries probably contributes to increasing severity and may complicate conflict termination and settlement. However, of all conflicts active in at least one year of the five-year period 2002–06, 29% were inactive in the next five-year period 2007–11. For conflicts in Muslim countries, the percentage was 27%, for conflicts with Islamist insurgencies 31%, and for other conflicts 28%. Thus, at least for this time period, there are only marginal differences between these categories with regard to the rate at which the conflicts are resolved.3

Figure 5 shows the number of battle deaths in interstate wars. In much of the period after World War II, interstate wars were the most severe, with the Korean War (1950–53) and the Vietnam War (1965–75) heading the list. However, the severity of interstate wars has decreased dramatically and the most recent large interstate war was between two Muslim countries, Iran and Iraq (1980–88). War is now largely a question of civil war and increasingly a plague on Muslim countries, as shown in Figure 4. Of the 223,500 battle deaths that are estimated to have occurred from 2010 to 2014, no less than 209,000 (94%) were in Muslim countries. Despite the targeting of Christians and other religious minorities by the IS and other Islamist insurgents, the vast majority of the victims are most likely Muslims; but the battle deaths databases do not provide information on religious affiliation.

What can account for the violence among Muslims? One obvious possibility is the history of colonialism with its legacy of artificial boundaries imposed by European colonial powers, an issue that has arisen explicitly in the numerous conflicts between Israel and its neighbors as well as in the Iraqi invasion of Kuwait in 1990. Territorial conflicts are generally harder to resolve than other conflicts. Juergensmeyer (2010) interprets the rise of religious nationalism as a counter-reaction to a secular nationalism promoted by the colonial powers and associated with corrupt and inefficient governments in the post-colonial world.

Another more recent source of problems is the interventionist policy of major powers, generally with a Christian majority, such as the Soviet Union in Afghanistan from 1979 and the US and other Western powers in several countries after 9/11. As a result, seemingly stable dictatorships have been replaced with unstable semi-democracies in a number of Muslim countries, such as Afghanistan, Iraq, and Libya. While there were no recent outside interventions in Egypt and Syria prior to 2011, the series of events known as the Arab Spring helped to diffuse regime change from the neighboring countries and Russian intervention eventually become an important factor in Syria. The increase in conflicts in Muslim countries after 2001 in absolute terms, but even more so in relative terms, suggests a reaction in the Muslim world to interventions by major powers.

Some find Islam as a religion to be more prone to fundamentalism and thus also to violence (Ben-Dor and Pedahzur, 2003). However, there are violent and peaceful elements in virtually all religions (Reichberg and Syse, 2014). All the Abrahamic religions (Judaism, Christianity, and Islam) have fundamentalist movements promoting a religious way of life, while in Hinduist and Buddhist movements, racial, ethnic, and religious goals tend to be mixed together (Almond et al., 2003). Whatever the religion, fundamentalist movements seek such radical change that in most polities peaceful accommodation is difficult; hence violence is more likely (Fox, 2013: 132).

Why do so many insurgents, particularly in the Muslim world, choose to rely on the more violent parts of the religious message? Some argue that the missionary character of Islam, as well as Christianity, makes for a more confrontational stance. Samuel P Huntington (1996) famously predicted that the end of the East–West confrontation would be followed by a “clash of civilizations.” Quantitative research has failed to find much support for this idea (Russett et al., 2000). However, the dominant pattern now seems to be a clash within the Muslim world, a situation simplified by Huntington (1996: 258) in his comment that Islam has “bloody innards” as well as “bloody boundaries.” Recently, the civil wars in the Muslim world have spilled over into non-Muslim countries, too, as evidenced by terrorist acts in Paris and elsewhere in 2015–16, but the number of victims is low compared with what Muslim countries have experienced and do not exceed the number of European victims of terrorism by Irish nationalists and right- and left-wing political extremists in Western Europe in the 1970s. As recently as 2011, the bloodiest terrorist incident in Europe was the anti-jihadist solo attack in Norway (York, 2015).

Conflicts with a religious dimension seem to be particularly intractable, but why does this affect the Muslim world more than others? One perspective is that Muslim countries have failed to adopt some of the changes that have led to a decline of violence in other parts of the world, such as secularization and increased respect for human rights. Others focus on how Muslim countries lag behind in economic and political development. For instance, scholars have found Muslim countries to be “democratic underachievers,” particularly with regard to women’s rights (Fish, 2002). Some of them are caught in a “resource curse,” with heavy dependence on export of raw materials and oil in particular. During a long period of high oil prices, oil-rich countries in the region have been able to channel resources to opposition movements that could undermine the position of their rivals in the region. Muslim countries also have a larger-than-average youth bulge (Karakaya, 2015), another factor associated with internal conflict.

A study by Sørli et al. (2005) found that Islam did not make a significant contribution to explaining the frequent incidence of conflict in the Middle East, once regime type, level of development, and other variables had been accounted for. Karakaya (2015) found that the increased conflict proneness of Muslim countries disappears when controlled for economic development, state repression, oil dependency, and the size of the youth bulge. But if these factors are themselves influenced by religion, this does not prove that religion is unimportant. A study by de Soysa and Nordås (2007), that used a more fine-grained variable of religious belonging, found that Catholic countries engaged in more violent internal repression than Muslim countries in the period 1980–2000, but this study also included control variables that may reasonably be part of the explanation for why Muslim countries experience more repression. Similar objections can also be raised against the work of Russett et al. (2000). More sophisticated causal models are needed to assess whether religion itself plays a role in armed conflict. It would also be useful to distinguish between varieties of the major religions. Much of the current violence in the Muslim world can be traced to the conflicts between the Sunni and Shia denominations, just as the war in Croatia in the first half of the 1990s pitted Catholics against Orthodox Christians.

If Muslim countries are overrepresented as far as internal armed conflict is concerned, what about other forms of violence? Table 2 reviews several indicators for the post-Cold War period. Muslim countries are overrepresented in interstate violence as well as four indicators of internal violence besides intrastate conflict – one-sided violence (violence against unorganized civilians), non-state violence (conflicts where none of the parties are the government), serious human rights violations, and the use of the death penalty. Hinduist countries come out with more than average violence on five of the six indicators, Buddhist countries on four, Judaist countries on two, countries with an Unaffiliated majority also on two, and Folk religion on just one. But, as already noted, these are relatively small groups of countries, and so count for less in the global picture. Christian countries are below average on all the indicators of violence. In terms of the number of casualties, intrastate armed conflict (civil war) is the most serious problem during this period.

Table 2. Religion and the relative incidence of violence, 1989–2014.

But while many Muslim countries suffer from violence, this is not true of all of them. Table 3 paints a slightly more optimistic picture of the state of the Muslim world. Here, the countries are ranked by the size of the Muslim population. While six of the 10 countries on this list experienced low-level internal conflict in 2014, only three experienced violence at the level of civil war. Moreover, four of the five countries with the largest Muslim population were free of civil war and have been so for a decade (India) or more (Bangladesh, Egypt, Indonesia). While these countries are not free from violent unrest, they have escaped the worst excesses.

Table 3. Current internal armed conflict and civil war in the 10 countries with the largest Muslim population.

We leave the argument there. The persistence of armed conflict in many Muslim countries and an increased use of violence in several of these conflicts is a major tragedy, particularly for the civilian population. The populations of these countries are well aware of this problem. An international opinion poll (Pew, 2014) showed that in the Middle East “religious and ethnic hatred” was seen as posing “the greatest threat to the world,” while in the US and Europe inequality occupied the top problem spot. Because of higher fertility rates in many Muslim countries, Islam is likely to grow faster than any other religion (Pew, 2015). Accounting for violence in Muslim countries is an urgent topic for scholars, and resolving religious conflicts is a priority task for policymakers. Hopefully, the data reported here can provide useful tools for further studies.