خوارج
Khawārij
Group
An early group who seceded from Ali’s army after Siffin (657), and who held that a Muslim committing a major sin ceases to be a believer.
What it means
After Ali agreed to arbitration with Muawiya they left, saying “judgement belongs only to God”, and turned against both. They killed Ali in 661. The Prophet foretold a people who would recite the Quran without it passing their throats, and would leave religion like an arrow from its game (Sahih al-Bukhari, Sahih Muslim), and the mainstream understood this to mean them.
What the sources say
Mainstream scholars made the Kharijite excess an object lesson: declaring other Muslims unbelievers (takfir) for sin is the error the Kharijites made and that the main schools have always warned against. The Ibadi school of Oman, which descends from moderate early Kharijism, rejects the extremist label.