Kharijites (Collective Plural Arabic: الخارجية, translit.: al-Khārijiyyah; Multiple Plural Arabic: خوارج, translit.: Khawārij; Singular Arabic: خارجي, translit.: Khāriji; literally ‘those who went out') is a general term describing former Muslims who, while initially supporting the authority of Ali ibn Abi Talib, the son-in-law and cousin of the Islamic prophet Muhammad, then later rejected his leadership. They first emerged in the late 7th century, concentrated in today’s southern Iraq, and are distinct from Sunni Muslims and Shi’a Muslims. With the passage of time the Kharijite groups fell greatly in their numbers and their beliefs did not continue to gain any traction in future generations.
From their essentially political position, the Kharijites developed extreme doctrines that further set them apart from both mainstream Sunni and Shiʿa Muslims. The Kharijites were particularly noted for adopting a radical approach to Takfir, whereby they declared other Muslims to be unbelievers and therefore deemed them worthy of death. The Kharijites were also known historically as the Shurah (Arabic: الشُراة, translit.: Shurāh),[A] literally meaning “the buyers” and understood within the context of Islamic scripture and philosophy to mean “those who have traded the mortal life (al-Dunya) for the other life [with God] (al-Aakhirah)”, which, unlike the term Kharijite, was one that many Kharijites used to describe themselves.
One of the early Kharijite groups was the Harouriyyah; it was notable for many reasons, among which was its ruling that a Harūrī, Abd-al-Rahman ibn Muljam, was the assassin of Caliph Alī.
The origin of Kharijism lies in the first Islamic civil war, the struggle for political supremacy over the Muslim community in the years following the death of Muhammad. After the third caliph (Uthman ibn Affan), a struggle for succession ensued between Caliph Ali and Muʿāwiyah, the governor of Syria and cousin of Uthman, in league with a variety of other opponents.
In 657, Alī’s forces met Muʿāwiyah’s at the Battle of Siffin. Initially, the battle went against Muʿāwiyah but on the brink of defeat, Muʿāwiyah directed his army to hoist Qur’āns on their lances. This initiated discord among some of those who were in Alī’s army. Muʿāwiyah wanted to put the dispute between the two sides to arbitration in accordance with the Qur’an. A group of Alī’s army mutinied, demanding that Alī agree to Muʿāwiyah’s proposal. As a result, Alī reluctantly presented his own representative for arbitration. The mutineers, however, put forward Abu Musa al-Ashʿari against Alī’s wishes.
Muʿāwiyah put forward ‘Amr ibn al-‘As. Abu Musa al-Ashʿari was convinced by Amr to pronounce Alī’s removal as caliph even though Ali’s caliphate was not meant to be the issue of concern in the arbitration. The mutineers saw the turn of events as a fundamental betrayal of principle, especially since they had initiated it; a large group of them repudiated Alī.
Citing the verse “No rule but God’s,” an indication that a caliph is not a representative of God, this group turned on both Alī and Muʿāwiya, opposing Muʿāwiya’s rebellion against one they considered to be the rightful caliph, and opposing ʻAlī for accepting to subject his legitimate authority to arbitration, thus giving away what was not his, but rather the right of the people. They became known as Kharijites: Arabic plural khawārij, singular Khārijī, derived from the verb kharaja “to come out, to exit.”
ʻAlī quickly divided his troops and ordered them to catch the dissenters before they could reach major cities and disperse among the population. Alī’s cousin and a renowned Islamic jurist, Abdullah ibn Abbas, pointed out the grave theological errors made by the Kharijites in quoting the Qur’an, and managed to persuade a number of Kharijites to return to Alī based on their misinterpretations. ʻAlī defeated the remaining rebels in the Battle of Nahrawan in 658 but some Kharijites survived.
Among the surviving Kharjites, three of them gathered in Mecca to plot a tripartite assassination attempt on Muʿāwiyah ibn ʾAbī Sufyān, ‘Amr ibn al-‘As and Alī ibn Abī Ṭālib. The assassination attempts were to occur simultaneously as the three leaders came to lead the morning prayer (Faj’r) in their respective cities of Damascus, Fustat and Kufa. The method was to come out of the prayer ranks and strike the targets with a sword dipped in poison.
Muawiya escaped the assassination attempt with only minor injuries. While Amr was sick and the deputy leading the prayers in his stead was martyred. However, the strike on Ali by the assassin, Abdur-Rahmaan ibn-Muljim, proved to be a fatal one. Ali was gravely injured with a head wound and succumbed to his injuries a few days later.
The circumstances in which Ali was attacked is subject to debate; where some scholars maintain that he was attacked outside the mosque, others state that he was attacked while initiating the prayer, still others reiterate that ibn-Muljim assaulted him midway through the prayer, while Ali was prostrating.
All the assassins were captured, tried and sentence to death in accordance with Islamic laws.
The Ibadis, a group who stemmed from the same mother group as the Kharijites, have survived into the present day. They form a significant part of the population of Oman (where they first settled in 686), and there are smaller concentrations of them in the M’zab of Algeria, Jerba in Tunisia, Jebel Nafusa in Libya, and Zanzibar.
IBADI ISLAM: AN INTRODUCTION
Valerie J. Hoffman (Professor of Islamic Studies at the University of Illinois)
Ibadism, a distinct sect of Islam that is neither Sunni nor Shi‘i, exists mainly in Oman, East Africa, the Mzab valley of Algeria, the Nafus mountains of Libya, and the island of Jerba in Tunisia. The sect developed out of the seventh-century Islamic sect known as the Khawarij, and shares with that group the desire to found a righteous Muslim society and the belief that true Muslims are only to be found in their own sect. Ibadis refer to themselves as “the Muslims” or “the people of straightness” (ahl al-istiqama). Nonetheless, Ibadis see themselves as quite different from Khawarij.
Whereas the Khawarij had labeled all Muslims who committed a grave sin without repentance mushrikun–i.e., unbelievers whose guilt is tantamount to idolatry and merits the capital punishment deserved by all apostates of the faith–Ibadis see such people as kuffar ni‘ma–monotheists who are ungrateful for the blessings God has bestown upon them. Ibadis distinguish between kufr ni‘ma and kufr shirk, which is the unbelief of idolatry. The Khawarij had not made such a distinction, and neither do the Sunni Muslims, who likewise equate kufr with unbelief but, unlike the Khawarij, maintain that a sinning Muslim is still a believer. The word kufr, which is typically translated into English as “unbelief,” literally means “ingratitude.” The characteristic position of human beings, according to the Qur’an, is not their ignorance of the existence of God, but their failure to be grateful for His kindness and blessings, which should prompt people to turn to Him in worship and give generous charity to the poor, orphans and widows. The Qur’an contrasts the believers, who are grateful (shakirun), with the unbelievers, who are ungrateful (kafirun).
The Ibadi attitude toward kuffar ni‘ma, whether they be sinning Ibadis or non-Ibadi Muslims, was that one should practice “dissociation” (bara’a) toward them. This “dissociation,” however, is usually an internal attitude of withholding “friendship” (wilaya), rather than outright hostility. Nonetheless, non-Ibadis who call themselves Muslims and pray facing the direction of the Ka‘ba are ahl al-qibla, not idolaters. They may be kuffar, but not in the sense of idolatry, only in the sense of kufr ni‘ma outlined above. The practice of dissociation (bara’a) does not imply enmity. Nur al-Din al-Salimi (1869-1914) clarified this when asked about the difference between dissociation from an unbeliever (bara’at al-mushrik) and dissociation from a corrupt monotheist (bara’at al-muwahhid al-fasiq). Salimi replied:
Although the mushrik is farther [from the truth] than the corrupt monotheist, both are cursed. Nonetheless, the Law allows certain things with the corrupt monotheist that it does not allow with the polytheist, such as intermarriage, eating their slaughtered animals, inheritance, giving the greeting of peace, saying “God bless you” if he sneezes, praying behind him, praying over him if he dies, accepting his testimony, and interacting with him in all worldly matters just as one would interact with Muslims with whom one has wilaya.
It is interesting to note that British observers of Omani rule in East Africa commented that Ibadis are the least fanatic and sectarian of all Muslims, and openly associate with people of all faiths and pray together with Sunni Muslims. Hostile action is reserved for one type of person: the unjust ruler who refuses to mend his ways or relinquish his power.
In theology, the Ibadis adopt the positions of the Mu‘tazila on the questions of tawhid: rejecting a literal interpretation of all anthropomorphic descriptions of God; denying the possibility of seeing God in this life or the afterlife; rejecting the existence of eternal attributes in God that are distinct from His essence; and upholding the doctrine of the creation of the Qur’an. They also part ways with Sunni Muslims in their condemnation of ‘Uthman, ‘Ali and Mu‘awiya and their rejection of the Prophet’s intercession on behalf of grave sinners and of all possibility of rescue from hellfire: punishment in hellfire is eternal, as the Qur’an says. They do not uphold the notion of an intermediate position between faith and kufr, but, as we have already indicated, they distinguish between different types of kufr, drawing a sharp distinction between kufr ni‘ma and kufr shirk. However, on the question of free-will vs. predestination the Ibadi position is virtually identical to that of al-Ash‘ari: God is the creator of all human acts, which are termed “acquisitions.”
There are minor differences between the prayer observances of Ibadis and Sunnis. Ibadis, like the Shi‘a and the Malikis, pray with their arms down at their sides. They do not say Amin after the Fatiha, and they do not say the qunut invocation in the fajr prayer. They believe that Friday prayer should be held only in major cities in which justice prevails–meaning that for centuries Ibadis did not observe congregational prayer because of the lack of a just Imam–and they reject the blessing of tyrannical rulers in the khutba.
The righteous Imamate is a topic of great importance in Ibadi legal literature. The Imam should be chosen for his knowledge and piety, without any regard to race or lineage. He should be chosen by the elders of the community, who are also obligated to depose him if he acts unjustly.
The Wahhabi movement has been referred to as the modern Khawarij by 18th century Hanafi scholar Ibn Abidin.
The Islamic State of Iraq and the Levant has been called Khawarij by some scholars.
Beliefs and practices
Early Muslim governance
The Kharijites considered the caliphate of Abu Bakr and Umar to be rightly guided but believed that Uthman ibn Affan had deviated from the path of justice and truth in the last days of his caliphate, and hence was liable to be killed or displaced. They also believed that Ali ibn Abi Talib committed a grave sin when he agreed on the arbitration with Muʿāwiyah. In the Battle of Siffin, Ali acceded to Muawiyah’s suggestion to stop the fighting and resort to negotiation. A large portion of Ali’s troops (who later became the first Kharijites) refused to concede to that agreement, and they considered that Ali had breached a Qur’anic verse which states that The decision is only for Allah (Qur’an 6:57), which the Kharijites interpreted to mean that the outcome of a conflict can only be decided in battle (by God) and not in negotiations (by human beings).
The Kharijites thus deemed the arbitrators (Abu Musa al-Ashʿari and Amr Ibn Al-As), the leaders who appointed these arbitrators (Ali and Muʿāwiyah) and all those who agreed on the arbitration (all companions of Ali and Muʿāwiyah) as Kuffār (disbelievers), having breached the rules of the Qur’an. They believed that all participants in the Battle of Jamal, including Talha, Zubair (both being companions of Muhammad) and Aisha had committed a Kabira (major sin in Islam). 
Doctrinal differences with other sects
The differences between the Sunni, Shiʿa, and the Kharijites are the following:
Sunnis accept Ali as the fourth rightly guided Caliph, and also accept the three Caliphs before him, who were elected by their community. Shi’a believe that the imaamate was the right of Ali, and the rule of the first three Rashidun caliphs was unlawful.
Kharijites insist that any Muslim could be a leader of the Muslim community and had the right to revolt against any ruler who deviated from their interpretation of Islam.
Kharijites reject the doctrine of infallibility for the leader of the Muslim community, in contrast to Shi’a but in agreement with Sunnis.
Modern-day Islamic scholar Abul Ala Maududi wrote an analysis of Kharijite beliefs, marking a number of differences between Kharijism and Sunni Islam.
The Kharijites believed that the act of sinning is analogous to Kufr (disbelief) and that every grave sinner was regarded as a Kāfir (disbeliever) unless he repents. With this argument, they denounced all the above-mentioned Ṣaḥābah and even cursed and used abusive language against them.
Ordinary Muslims were also declared disbelievers because first, they were not free of sin; secondly they regarded the above-mentioned Ṣaḥābah as believers and considered them as religious leaders, even inferring Islamic jurisprudence from the Hadeeth narrated by them. 
They also believed that it is not a must for the caliph to be from the Quraysh. Any pious Muslim nominated by other Muslims could be an eligible caliph. Additionally, Kharijites believed that obedience to the caliph is binding as long as he is managing the affairs with justice and consultation, but if he deviates, then it becomes obligatory to confront him, demote him and even kill him. 
Regarding Islamic law, the Kharijites considered the Qur’an as the source for Islamic jurisprudence but regarding the other two sources (Hadith and Ijma) their concepts were different from ordinary Muslims. 
Ihsan Abbas, another modern-day Muslim scholar, analyzed the Kharijites from their own writings, a perspective which has rarely been taken by other Sunni writers.
Based on their poetry, Abbas divided Kharijite expression into three categories of focus: the strong desire of Kharijites for martyrdom and dying for the sake of God, detailed descriptions of how Kharijites defined a just and pious ruler, and their universal tendency to blame the self for failing to establish the previous two categories.