Eligible and Ineligible In-groups

Excerpt from J. M. Berger's Extremism (The MIT Press Essential Knowledge series) (click here to buy):  

Extremist ideologies define constrictive or exclusive identities and enforce rigid boundaries between in-groups and out-groups. Ironically, this quest to promote greater group cohesion can itself fracture the in-group. Shared negative attitudes toward outsiders can help strengthen bonds around certain in-group members, but they also put pressure on members of the in-group to adopt more hostile attitudes toward the out-group. When this happens, the unity of the in-group comes under pressure. 

Remember that most broad identities are not extremist. It’s not extremist to identify as Anglo-Saxon or African American, Christian, or Muslim. Extremist movements like Christian Identity and Islamic State sprout from these broad identities, but they quickly take on their own distinct character. When an extremist identity emerges, it must recruit adherents from the broader identity group from which it came. This process requires extremists to divide the in-group into subcategories. 

As extremist movements form robust organizational structures and begin to recruit, these subcategories take on surpassing importance. A mature extremist organization must address three crucial subdivisions in its ideological formulations: 

Extremist in-group: The extremist movement or organization itself. For a highly developed movement like Islamic State, this category may include both formal members and active supporters. 

Eligible in-group: The broad identity collective that an extremist organization claims to represent and from which it seeks to recruit. For Islamic State, the eligible in-group consists of Sunni Muslims. All Sunni Muslims are eligible to join the Islamic State. For the KKK, the eligible in-group consists of White (usually Protestant) Americans. The extremist group often believes it represents the purest iteration of the eligible group. 

Ineligible in-group: In-group members who are at risk of being expelled from the in-group, in the view of an extremist movement. When members of the eligible in-group reject the extremist movement, extremists may in turn seek to eject them from the eligible in-group. As an extremist movement becomes more developed, it begins to treat eligibility as obligation. In other words, a group like Islamic State believes not only that Sunni Muslims are eligible to join its movement but that they are obligated to do so. For example, Islamic State often declares Sunni Muslims who oppose its teachings and tactics to be apostate from the religion of Islam as a whole. Similarly, neo-Nazi movements believe that all White people are morally obligated to support them, and those who do not can be branded "race traitors" and singled out for especially harsh punishments, up to and including death. The infamous "Day of the Rope" in The Turner Diaries refers to the public execution of White people perceived to have married, collaborated with or supported non-White people.