I was going through Shaykh Abdal Qadir Jailani's input on khawarij and noticed the similarities with groups today:
Yet another name that has been given to them is "the Vendors" [Shurat], because of their assertion: "We have sold our own selves for the sake of Allah's cause [sharaina anfusana fi'llah]," or in other words: "We have traded them in exchange for Allah's spiritual reward and His good pleasure."
Interestingly we see salafis love similarily labelling and posturing and boasting themselves as being a "mujahideen" and so forth.
They have separated themselves off from the religious community [milla], breaking loose from it and from the loyal congregation [jama'a].
They have branded all who oppose them as unbelievers [kaffaru man khalafahum].
Another typical character that requires no explanation.
to begin the fast [sawm] before the sighting of the new moon [of the month of Ramadan], and to break the fast [fitr] in like manner [before the end of Ramadan has been established by the sighting of the new moon of Shawwal].
Similar to salafis today who abondoned the method of visual moon sighting.
They also maintained that there is no need for an Imam, since what is necessary is knowledge of the Book of Allah, and that alone is quite sufficient.
This is foundation of salafism typical of their "I follow Quran and Sunnah" lamadhabi/anti-traditional doctrine and protestant self learnt scholarship.
The Azariqa also consider it permissible to kill young children, meaning the offspring of those who attribute partners to Allah [awlad al-mushrikin].
They are in agreement with the Azariqa on the permissibility of taking women captives from among the unbelievers [kuffar], and of killing their infant children inadvertently, on the strength of [their interpretation of] the words of Allah (Exalted is He): [And Noah said: "My Lord,] do not leave upon the earth even one of the unbelievers." (71:26)