In The Name of Allaah, The Most Merciful, The Bestower of Mercy
Summarized Benefits from the audio in this link: https://soundcloud.com/ahlalathar/28-1435-1
 Shaikhul Islaam Ibn Taymiyyah and other scholars made it known that some of the Khawaarij do not make takfeer of Muslims for every type of major sin; rather they only make takfeer for some major sins and not others.
Many of the people say: ”’O brother! These people (i.e. some of the khawaarij at present) do not make takfeer of the Muslims for committing adultery or for consuming alcohol etc…so how can you call them khawaarij?!”
This affair has become confusing for many of the people because they do not know that some of the khawaarij make takfeer on account of a major sin committed by a Muslim and others amongst the khawaarij do not do so. And for this reason they make takfeer of the one who rules by other than what Allaah has revealed, when it is the case that ruling by other than what Allaah has revealed is a major sin from the major sins. [See here detailed explanation of this affair http://www.spubs.com/sps/sp.cfm?subsecID=MNJ05&articleID=MNJ050003&articlePages=1 http://www.spubs.com/sps/sp.cfm?subsecID=MNJ05&articleID=MNJ050018&articlePages=1]
 The khawaarij are all agreed upon the fact that the one who does not rule by what Allaah has revealed is a disbeliever. And this is why Shaikhul Islaam Ibn Taymiyyah (rahimahullaah) said about the Ayah: [وَمَن لَّمۡ يَحۡكُم بِمَآ أَنزَلَ ٱللَّهُ فَأُوْلَـٰٓٮِٕكَ هُمُ ٱلۡكَـٰفِرُونَ – And whosoever does not judge by what Allah has revealed, such are the Kafirun (i.e. disbelievers – of a lesser degree as they do not act on Allah’s Laws )—None uses the generality of this ayah as evidence (for takfeer) except the khawaarij. [Again see detailed explanation of this affair here:http://www.spubs.com/sps/sp.cfm?subsecID=MNJ05&articleID=MNJ050003&articlePages=1http://www.spubs.com/sps/sp.cfm?subsecID=MNJ05&articleID=MNJ050018&articlePages=1]
Therefore, it is not a condition that a person has to make takfeer for every type of major sin in order to be regarded a kharaaji.
 One should not be deceived by what the khawaarij manifest in exalting the Islamic Law
It is upon the Muslims to refer the affairs back to its people (i.e. to those who are qualified to speak in these affairs and have been entrusted with it). Allaah said:
وَإِذَا جَآءَهُمۡ أَمۡرٌ۬ مِّنَ ٱلۡأَمۡنِ أَوِ ٱلۡخَوۡفِ أَذَاعُواْ بِهِۦۖ وَلَوۡ رَدُّوهُ إِلَى ٱلرَّسُولِ وَإِلَىٰٓ أُوْلِى ٱلۡأَمۡرِ مِنۡہُمۡ لَعَلِمَهُ ٱلَّذِينَ يَسۡتَنۢبِطُونَهُ ۥ مِنۡہُمۡۗ وَلَوۡلَا فَضۡلُ ٱللَّهِ عَلَيۡڪُمۡ وَرَحۡمَتُهُ ۥ لَٱتَّبَعۡتُمُ ٱلشَّيۡطَـٰنَ إِلَّا قَلِيلاً۬
”When there comes to them some matter touching (public) safety or fear, they make it known (among the people), if only they had referred it to the Messenger or to those charged with authority among them, the proper investigators would have understood it from them (directly). Had it not been for the Grace and Mercy of Allah upon you, you would have followed Shaitan (Satan), save a few of you.” [Soorah An-Nisaa. Ayah 83]
When the Muslim is confronted with a fitna or an affair of fear or public safety, he should ask the scholars. At present Al-Allaamah Saaleh al-Fawzaan and others amongst the people of knowledge say that Daa-ish are khawaarij, people of fitnah and evil people. They slaughter the Muslims.
These ones (Daa-ish/ ISIS) believe that whoever does not believe in the pledge given to Abubakr Al-Baghdaadi is a disbeliever, then how can it be said that they do not make takfeer of the Muslims. They say that all the Muslim rulers are disbelievers-this is the creed of Daa-ish. If these people (Daa-ish) are not khawaarij, then who are the khawaarij?! These ones (i.e. Daa-ish) say that whoever does not give consideration to the pledge given to AbuBakr Al-Baghdaadi is a disbeliever and that all the Muslim Rulers are disbelievers!
As for their manifestation and exaltation of the Islamic laws, practices and implementation of the Islamic penal codes; then this is something well known of the khawaarij. The Prophet (sallal-laahu-alayhi-wasallam) said: ”One of you would belittle his own prayer when compared to their prayer and his fasting compared to their fasting….”
Therefore, they manifest an exaltation of the sharee-ah affairs, such as the prayer, the zakat and establishment of the Islamic penal codes, however they are upon a corrupt creed. It is not befitting to be deceived by what they manifest or what is manifested from them with regards to exaltation of the share-ah.
Why did the khawaarij of old fight the Sahaabah (the Companions of the Prophet) when they (i.e. khawaarij) announced an exaltation of the sharee-ah?! They (i.e. khawaarij) said: ‘’There is no judgement except with Allaah.’’ So Ali (radiyallaahu-anhu) said to them: ‘’You have uttered a statement of truth by way of which you intend falsehood.’’ They manifested exaltation of the share-ah and an establishment of it in order to make lawful the shedding of the blood of the Sahaabah. They declared the Sahaabah disbelievers and killed them. They made lawful the shedding of the blood of the Sahaabah in the name of the Sharee-ah, saying: ‘’There is no judgement except with Allaah’’, so Ali (radiyallaahu-anhu) said to them: ‘’You have uttered a statement of truth by way of which you intend falsehood.’’
This is the path of the khawaarij since the early days. Therefore, it is obligatory to be eager for knowledge and to attach oneself to the scholars of the Sunnah; the scholars of hadeeth and the fuqahaa, so that one does not fall into the schemes of these khawaarij imposters.