Ibn Taymiyyah writes:” The Kharijite sect was the first to declare Muslims to be unbelievers because of their sins. They charged as unbelievers whoever disagreed with their innovations and they made lawful the spilling of their blood. This is the condition of the people of innovation that they invent some religious innovation and then they excommunicate whoever disagrees with them concerning it. Rather, the people of the Sunnah and the community follow the Book and the Sunnah and they obey Allah and His Messenger and follow the truth. They have mercy upon the creation”.

(Majmu’ al-Fatawa 1/278)