Takfir

Takfir is an Arabic term which refers to a person (a Muslim, specifically) in a conscious and willing state of sin who is in danger of being rejected by the community of fellow Muslims for non-belief. Takfirism is the controversial process of declaring a Muslim a kafir, or unbelieving infidel.

Once a believer falls into sin, he is supposed to be admonished and granted time to repent. Scholars disagree how many believing witnesses are to approach the sinner with a warning and how long the sinner is given opportunity to change their behavior. Neither Osama bin Laden, nor Juhayman al-Otaybi who led the 1979 Grand Mosque Seizure were declared takfir by the Saudi religious establishment, only admonished to repent for causing the deaths of innocent people. Peter Edward Kassig, a humanitarian aid worker who converted to Islam and was never accused of killing anyone, was declared takfir by ISIS and beheaded. Some Salafists maintain it only takes one Muslim to declare another Muslim takfir, and thus a traitor to Islam - a more serious crime than being an simple ignorant infidel who never accepted the tawhid.