According to some Muslim authors, extremism within Islam goes back to the 7th century to the Kharijites. From their essentially political position, they developed extreme doctrines that 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.
Political Islam Part 75
