Sectarian violence and/or sectarian strife is a form of communal violence inspired by sectarianism, that is, between different sects of one particular mode of ideology or religion within a nation/community. Religious segregation often plays a role in sectarian violence.
According to the Stockholm International Peace Research Institute:
Traditionally, sectarian violence implies a symmetrical confrontation between two or more non-state actors representing different population groups.
Sectarian violence differs from the concept of race riot. It may involve the dynamics of social polarization, the balkanization of a geographic area along the lines of self-identifying groups, and protracted social conflict.
Some of the possible enabling environments for sectarian violence include power struggles, political climate, social climate, cultural climate, and economic landscape.
- Economic conflict: capitalist versus collectivist
- Political conflict: communist versus nationalist
- Christian conflict: Catholic versus Protestant
- Interreligious conflict: Muslim versus Christian, Muslim versus Buddhist
- Islamic conflict: Shia versus Sunni
Although the First Crusade was initially launched in response to an appeal from Byzantine Emperor Alexios I Komnenos for help in repelling the invading Seljuq Turks from Anatolia, one of the lasting legacies of the Crusades was to "further separate the Eastern and Western branches of Christianity from each other."
European wars of religion
Following the onset of the Protestant Reformation, a series of wars were waged in Europe starting circa 1524 and continuing intermittently until 1648. Although sometimes unconnected, all of these wars were strongly influenced by the religious change of the period, and the conflict and rivalry that it produced. According to Miroslav Volf, the European wars of religion were a major factor behind the "emergence of secularizing modernity".
In the St. Bartholomew's Day massacre followers of the Roman Catholic Church killed up to 30,000 Huguenots (French Protestants) in mob violence. The massacres were carried out on the national day celebrating Bartholomew the Apostle. Pope Gregory XIII sent the leader of the massacres a Golden Rose, and said that the massacres "gave him more pleasure than fifty Battles of Lepanto, and he commissioned Giorgio Vasari to paint frescoes of it in the Vatican". The killings have been called "the worst of the century's religious massacres", and led to the start of the fourth war of the French Wars of Religion.
Since the 16th century there has been sectarian conflict of varying intensity between Roman Catholics and Protestants in Ireland. This religious sectarianism is connected to a degree with nationalism. Northern Ireland has seen inter-communal conflict for more than four centuries and there are records of religious ministers or clerics, the agents for absentee landlords, aspiring politicians, and members of the landed gentry stirring up and capitalizing on sectarian hatred and violence back as far as the late 18th century.
William Edward Hartpole Lecky, an Irish historian, wrote "If the characteristic mark of a healthy Christianity be to unite its members by a bond of fraternity and love, then there is no country where Christianity has more completely failed than Ireland".
Reactions to sectarian domination and abuse have resulted in accusations of sectarianism being levelled against the minority community. It has been argued, however, that those reactions would be better understood in terms of a struggle against the sectarianism that governs relations between the two communities and which has resulted in the denial of human rights to the minority community.[better source needed]
Steve Bruce, a sociologist, wrote;
The Northern Ireland conflict is a religious conflict. Economic and social considerations are also crucial, but it was the fact that the competing populations in Ireland adhered and still adhere to competing religious traditions which has given the conflict its enduring and intractable quality.:249 Reviewers agreed "Of course the Northern Ireland conflict is at heart religious".
John Hickey wrote;
Politics in the North is not politics exploiting religion. That is far too simple an explanation: it is one which trips readily off the tongue of commentators who are used to a cultural style in which the politically pragmatic is the normal way of conducting affairs and all other considerations are put to its use. In the case of Northern Ireland the relationship is much more complex. It is more a question of religion inspiring politics than of politics making use of religion. It is a situation more akin to the first half of seventeenth century England than to the last quarter of twentieth‑century Britain.
The period from 1969 to 2002 is known as "The Troubles". Nearly all the people living in Northern Ireland identified themselves as belonging to either the Protestant or the Catholic community. People of no religion and non-Christian faiths are still considered as belonging to one of the two "sects" along with churchgoers. In this context, "Protestants" means essentially descendants of immigrants from Scotland and England settled in Ulster during or soon after the 1690s; also known as "Loyalists" or "Unionist" because they generally support politically the status of Northern Ireland as a part of the United Kingdom. "Catholics" means descendants of the pre-1690 indigenous Irish population; also known as "Nationalist" and "Republicans"; who generally politically favour a united Ireland.
There are organizations dedicated to the reduction of sectarianism in Northern Ireland. The Corrymeela Community of Ballycastle operates a retreat centre on the northern coast of Northern Ireland to bring Catholics and Protestants together to discuss their differences and similarities. The Ulster Project works with teenagers from Northern Ireland and the United States to provide safe, non-denominational environments to discuss sectarianism in Northern Ireland. These organizations are attempting to bridge the gap of historical prejudice between the two religious communities.
Howard Goeringer criticizes both the "Catholic Pope and the Orthodox Patriarch" for failing to condemn the "deliberate massacre of men, women and children in the name of 'ethnic cleansing' as incompatible with Jesus' life and teaching."
The majority of Rwandans, and Tutsis in particular, are Catholic, so shared religion did not prevent genocide. Miroslav Volf cites a Roman Catholic bishop from Rwanda as saying, "The best cathechists, those who filled our churches on Sundays, were the first to go with machetes in their hands". Ian Linden asserts that "there is absolutely no doubt that significant numbers of prominent Christians were involved in sometimes slaughtering their own church leaders." According to Volf, "what is particularly disturbing about the complicity of the church is that Rwanda is without doubt one of Africa’s most evangelized nations. Eight out of ten of its people claimed to be Christians."
When the Roman Catholic missionaries came to Rwanda in the late 1880s, they contributed to the "Hamitic" theory of race origins, which taught that the Tutsi were a superior race. The Church has been considered to have played a significant role in fomenting racial divisions between Hutu and Tutsi, in part because they found more willing converts among the majority Hutu. The Organisation of African Unity (OAU) report on the genocide states,
In the colonial era, under German and then Belgian rule, Roman Catholic missionaries, inspired by the overtly racist theories of 19th century Europe, concocted a destructive ideology of ethnic cleavage and racial ranking that attributed superior qualities to the country's Tutsi minority, since the missionaries ran the colonial-era schools, these pernicious values were systematically transmitted to several generations of Rwandans…
The Roman Catholic Church argues that those who took part in the genocide did so without the sanction of the Church. Although the genocide was ethnically motivated and religious factors were not prominent, the Human Rights Watch reported that a number of religious authorities in Rwanda, particularly Roman Catholic, failed to condemn the genocide publicly at the time. Some Christian leaders have been convicted by the International Criminal Tribunal for Rwanda for their roles in the genocide. These include Rwandan Roman Catholic priests and nuns as well as a Seventh-day Adventist Church pastor.
Scotland suffers from a spill-over of Northern Irish sectarianism due to many people having links to certain communities living in the country, particularly in the West.
Glasgow's two largest and best supported football clubs, Celtic and Rangers subscribe to government initiatives and charities like the Nil by Mouth campaign are working in this area. Celtic have previously sent letters to every season ticket holder reminding supporters that any form of sectarianism is not welcome at Celtic Park. Rangers' equivalent anti-sectarian policy is called Follow With Pride.
Sectarian violence between the two major sects of Islam, Shia and Sunni, has occurred in countries like Pakistan, Iraq, Afghanistan, Bahrain, Lebanon etc. This violent conflict has roots in the political turmoil arising out of differences over the succession to Muhammad. Abu Bakr, a companion of Muhammad, was nominated by Umar and elected as the first Sunni Rightly Guided Caliph. However another group felt that Ali, the cousin and son-in-law of Muhammad, had been designated by Muhammad and is considered by Shia as the first Imam.
Abu Bakr was followed by Umar as caliph of the Rashidun Caliphate, then by Uthman ibn Affan and finally by Ali. Ali's right to rule was challenged by Muawiyah bin Abu Sufian, governor of Syria, who believed that Ali should have acted faster against the murderers of Uthman. The situation detoriated further when many of those responsible for the death of Uthman rallied behind Ali. However, later on, both the parties agreed to have some one as a judge between them. This led to the separation of an extremist group known as Kharijites from Ali's army, which pronounced the judgement belonged to God alone. A member of this group later assassinated Ali. At the demise of Muawiyah he appointed his son Yazid as his successor. The credentials of Yazid were challenged by Ali's son Hussein ibn Ali (and grandson of Muhammad). A battle at Karbala in Iraq led to the martyrdom of Hussein and dozens of others from Ahl al-Bayt (the members of the family of Muhammad).
This tragic incident created deep fissures in the Muslim society. The conflict that had started at a political plane intervened with the dogma and belief systems. Those who considered Ali to be the true heir to the Caliphate split away from the main corpus of Muslim society and traditions. They developed their distinct sect, known as "Shia" referring to Shian-e-Ali. The majority of Muslims are known as "Sunni" meaning "followers of the Traditions of The Prophet ". They are of the view that the bloody conflict between Ali and Muawiyah was a result of a tragic misunderstanding and regardless of who was wrong, the matter should have been solved peacefully.
In February 2006, more than 100 people were killed across Iraq, when violence between the two Muslim rival sects erupted. It has left over a hundred people dead and dozens of mosques and homes destroyed. 
In Pakistan sectarianism exhibited its first organized nature in early 1980 when two rival organizations were established: Tehrik-e-Jafaria (TFJ) (Organization of the Jafri (Shia) Law) represented Shia communities, and Sipah-e-Sahaba Pakistan (SSP) (Guardian of the Companions of the Prophet) representing Sunnis. The first major incident of this sectarian violence was killing of the Arif Hussain Hussaini, founding leader of TFJ in 1986. In retaliation Haq Nawaz Jhangvi, founder of the (SSP) was murdered. Since then internecine bloody vendetta has ensued. The focus of this violence has been Kurram, Hangu, Dera Ismail Khan, Bahawalpur, Jhang, Quetta,Gigit- Baltistan and Karachi.
The transformation of the sectarian conflict to a violent civil war in Pakistan coincided with the establishment of the Islamic republic in Iran and promotion of the Sunni religion and its incorporation in the state institutions by General Muhammad Zia-ul-Haq, regime in Pakistan.
The Iranian Revolution was led by Shia clerics, and it influenced Shia communities all over the world. In Pakistan Tehrik-e-Jafaria was established with the demands of enforcing the Shia Law. This demand was viewed as detrimental by the Sunni religious leaders. In response SSP was established by the Sunni extremist clerics. Many of these clerics had a background in the sectarian strife against the Ahmadis (a heterodox sect considered non-Muslim by majority of the Orthodox Schools)
Ahlu Sunna Waljama'a is a Somali paramilitary group consisting of Sufis and moderates opposed to the radical Islamist group Al-Shabaab. They are fighting to prevent Wahhabism from being imposed on Somalia and protecting the country's Sunni-Sufi traditions and generally moderate religious views.
The Syrian civil war gradually shifted towards a more sectarian nature. Pro-Assad militant groups are largely Shia, while anti-Assad militant groups are largely Sunni.
- Communalism (South Asia)
- Cypriot intercommunal violence
- Religious violence in India
- 2005 civil unrest in France
- 2005 Cronulla riots
- 2006 Brussels riots
- 2009 Boko Haram Uprising
- 2009 Gojra riots
- SIPRI Yearbook 2008: Armaments, Disarmament, and International Security. Stockholm International Peace Research Institute. 2008.
- Bellinger, Charles K. (2001). The genealogy of violence: reflections on creation, freedom, and evil. Oxford University Press US. p. 100.
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- H.G. Koenigsberger; George L.Mosse; G.Q. Bowler (1989). Europe in the Sixteenth Century, Second Edition. Longman. ISBN 0-582-49390-0.
- William Edward Hartpole Lecky (1892). A History of Ireland in the Eighteenth Century.
- Mulholland, P. (1999) Drumcree: A Struggle for Recognition
- Steve Bruce (1986). God Save Ulster. Oxford University Press. p. 249. ISBN 0-19-285217-5.
- David Harkness (October 1989). "God Save Ulster: The Religion and Politics of Paisleyism by Steve Bruce (review)". The English Historical Review. Oxford University Press. 104 (413).
- John Hickey (1984). Religion and the Northern Ireland Problem. Gill and Macmillan. p. 67. ISBN 0-7171-1115-6.
- Goeringer, Howard (2005). Haunts of Violence in the Church. p. 77.
- Volf, Miroslav (January 1999). "The Social Meaning of Reconciliation". Transformation: An International Journal of Holistic Mission Studies. 16 (1): 7–12.
- Linden, I. (1997). The Church and Genocide. Lessons from the Rwandan Tragedy. In G. Baum (Ed.), The Reconciliation of Peoples. Challenge to the Churches (pp. 43–55). Geneva: WCC Publications.
- Dictionary of Genocide, Samuel Totten, Paul Robert Bartrop, Steven L. Jacobs, p. 380, Greenwood Publishing Group, 2008, ISBN 0-313-34644-5
- "Rwanda: The Preventable Genocide". Organization of African Unity. 7 July 2000. Retrieved 20 November 2010.
- Dictionary of Genocide", Samuel Totten, Paul Robert Bartrop, Steven L. Jacobs, p. 380, Greenwood Publishing Group, 2008, ISBN 0-313-34644-5
- "Rwandan Genocide: The Clergy". Human Rights Watch. Retrieved 20 November 2010.
- "Rwandan bishop cleared of genocide". BBC News. 15 June 2000. Retrieved 23 May 2010.
- Small, Mike (8 August 2007). "Hymns of hatred at Ibrox Park". The Guardian. London. Retrieved 17 August 2010.
- Finer, Jonathan; Sebti, Bassam (24 February 2006). "Sectarian Violence Kills Over 100 in Iraq". The Washington Post.
- "Somali rage at grave desecration". BBC News. 8 June 2009.