Kharijite

Kharijites or Khawarij (الخوارج‎) were an ancient extremist group or sect during the first century in the history of Islam. They were known for conducting violence against fellow Muslims and for their rigid exclusivist doctrines. The group was active especially during the succession crisis after the death of Muhammad (known as "First Fitna"). Kharijites belived the will of God to be above people's arbitration and the acceptable leadership to be decided by battle. They are responsible for the assassination of Ali, who is mourned by Shi'a Muslims up to this day. Kharijites existed for hundreds of years. They built up their distinct doctrinal structure, which is obsolete today, except for the distant relative known as Ibadi Islam, which is popular only in Oman and tiny desert communities in North Africa. Ironically, the Ibadi are quite peaceful and known for producing almost no extremists. A modern historian describes Kharijites as "Bedouin nomads who resented the centralization of power in the new Islamic state that curtailed the freedom of their tribal society."

Why it matters
One of the core doctrinal tenets of Kharijite resembles that of today's Islamist terrorism or terrorism conducted in the name of Islam. Notably, they are quick to excommunicate (takfir) fellow Muslims for not following their normative teaching of Islam. This quick-takfirism is one of the principles of early Islamist thinker Sayyid Qutb's ideology (known as an older brother of ) which enabled the revolution against the despotic regime of the Arab world and killing of the Muslim government officials, military personnel, and other members of state apparatus in the name of Islam. In general, takfirism involves a cautious procedure and has not been employed by the majority of Muslim clerics, and it may be possible to say that Kharijites and modern Islamist terrorists are the exceptional cases which frequently use takfirism as a religious methodology.

As such, Kharijites are almost universally denounced by Muslims, both Sunni and Shi'a, and they are frequently invoked by Muslims to denounce the terrorist groups like Al-Qaeda and DAESH. This is an important point to see the line between even the staunchest hard-core conservative Muslims who advocate for Niqab and public gender segregation, and groups like Al-Qaeda and DAESH which commit violence and terrorism. In the Muslim worldview, terrorist groups are Kharijites, point blank period, and there's no room for conflating even the Saudi or Ayatollah's regime and DAESH because the former are not Kharijites, while the latter is. It's a relevant perspective to consider in the light of frequent confusion of valid criticism of Islam and Islamophobia; mere conservatism of Islam has a drastic difference from the possibility of them turning into terrorists because, in the eyes of Muslims, terrorism is as despicable as Kharijites and it's best avoided for them to behave as such.