The rise and successes of ISIS may at first glance appear unprecedented, and its extreme ideology as an aberrant distortion of traditional Islam. However, I will argue that some aspects of the ISIS phenomenon actually appear familiar when we consider them in deeper historical perspective, especially in the context of the kinds of arguments and rhetoric that have been employed by groups seeking to foment violence against their Muslim coreligionists. Here I will show that in its propaganda, ISIS uses themes and images drawn from the Qurʾān, as well as certain familiar tropes and topoi of Islamic history, in a fashion similar to the early Fatimid Empire, founded by a branch of the Shi’ah that established a caliphate based in North Africa and Egypt that eclipsed the Sunni caliphate of the Abbasids based in Baghdad. The ultra-militant vision of Islam and Muslim community promoted by ISIS is contrary to the ethos of Sunnism as it has generally been defined throughout its history; however, it does resemble the militant and perfectionist conception of Islam held by early sectarian groups like the Fatimids.