Who are the khawārij, are they disbelievers or Muslims?
Shaykh ʿAbd al-ʿAzīz ibn Bāz:
The khawārij are a (misguided) group that have extreme views. They are diligent in religious matters; they have diligence with regards to prayer, reading and other than that. However, they have extreme views: they declare sinful Muslims to be disbelievers (i.e. takfīr).
Due to the extremity of their (fanatical) immoderation, they view that whoever has fornicated has disbelieved, whoever has drunk alcohol has disbelieved, and whoever has been undutiful to his parents has disbelieved.
They declare sinful Muslims to be disbelievers on account of sins. The prophet ﷺ said regarding them:
“A set of people ‘mariqa’ (will emerge in latter times) when the Muslims are split-up, one of you would belittle his prayer in comparison to their prayer and his recitation of Qurʾān in comparison to their recitation of Qurʾān. They pass through and exit Islam and do not return to it”.
These people they are the khawārij. They have a trait of obstinacy.
If they were to read the Qurʾān, their recitation would impress you. If they were to pray, their prayer would impress you. However, they have extremism when it comes to declaring people disbelievers (apostates). They view that whoever has fornicated has disbelieved, and whoever has stolen has disbelieved, whoever has drunk alcohol has disbelieved and for this reason the prophet ﷺ said regarding them:
“They pass through and exit Islam like the piercing of an arrow through its target. If I were to come into proximity of them, I would most certainly kill them as the people of ʿĀd were killed. Wherever you (Muslim rulers) come across them, kill them, for certainly there is a reward for the one who kills them”.
The majority (of the fuqahā) hold the view that they (the khawārij) are sinners, innovators in the religion, and are astray. However, they do not declare them to be disbelievers, but the correct view is that they (the khawārij) are disbelievers due to this.
His statement ﷺ: “They pass through and exit from Islam and do not return to it” is proof that they are disbelievers. (Also) “If I were to come into proximity of them, I would most certainly kill them as the people of ʿĀd were killed”. The people of ʿĀd are (the) disbelievers (who rejected prophet Hūd ﷺ). The correct view and that which is apparent from the proofs is that they are –by way of this trait of obstinacy and declaring the Muslims to be disbelievers abiding in the hellfire for eternity, disbelievers by this; because they view a sinful Muslim to be a disbeliever abiding in the hellfire forever.
This (creed) is far astray –Allāh’s refuge is sought – leading the one who believes this to exit from the fold of Islam –we seek refuge in Allāh (from this).
We ask Allāh for pardon and wellbeing.