Takfiri

Takfiri  is an Arabic and Islamic term denoting a Muslim who excommunicates one of their coreligionists—i.e., who accuses another Muslim of being an apostate, or murtadd, 'one who turns back'.

According to the traditional interpretations of Islamic law (Sharia), the punishment for apostasy is death Potentially a cause of strife and violence within the Muslim community (ummah), an ill-founded accusation of takfir is considered a major forbidden act (haram) in Islamic jurisprudence, with one hadith declaring that one who wrongly declares another Muslim to be an unbeliever is themself an apostate. Takfirism has been called a "minority ideology" that "advocates the killing of other Muslims declared to be unbelievers".

The accusation itself, takfīr, is derived from the Arabic word kafir ('unbeliever') and described as when "one who is a Muslim is declared impure". In principle, in mainstream Sunni Islam, the only group authorized to declare another Muslim a kāfir are the scholars of Islam (ulama); this is done only if all the prescribed legal precautions have been taken. Traditionally, the declaration of takfīr was used against self-professed Muslims who denied one or more of the five pillars of Islam. Throughout the history of Islam, Islamic denominations and movements, such as Shia Islam and Ahmadiyya Islam, have been accused of takfīr and labeled as kuffār ('unbelievers') by Sunni leaders, becoming victims of religious discrimination, religious violence, and religious persecution. The term Takfiri has also been pejoritavely deployed by Shia jihadist groups to demonise and justify violence against Sunnis.

In the history of Islam, a sect originating in the 7th century CE known as the Kharijites carried out takfīr against both Sunnī and Shīʿa Muslims, becoming a dominant source of intra-Islamic insurrection against caliphates for centuries. Since the latter half of the 20th century, takfīr has also been used for "sanctioning violence against leaders of Islamic states" who do not enforce Sharia or are otherwise "deemed insufficiently religious". This arbitrary application of takfīr has become a "central ideology" of insurgent Wahhabi-Salafi jihadist extremist and terrorist groups, particularly al-Qaeda and Islamic State of Iraq and the Levant (ISIL), which have drawn on the ideas of the medieval Islamic scholars Ibn Taymiyyah and Ibn Kathir, and those of the modern Islamist ideologues Sayyid Qutb and Abul A'la Maududi. The practice of takfīr has been denounced as deviant by mainstream branches of Islam and Muslim scholars, such as Hasan al-Hudaybi (died 1977) and Yusuf al-Qaradawi.