Islam, like all religions, offers solutions to existential anxieties. This article provides a timely analysis of Islamic mainstream and extremist doctrinal and ritualistic structures through an existential lens to gain an understanding of the psychological underpinnings of Islamic extremism. It is shown that Islam offers an interlocking tradeoff among the ultimate concerns of meaning, freedom, and death in addition to individual solutions for each. It is argued that this container for holding existential anxiety is under assault by modernization and that the resultant psychic pressure is at the core of the psychology of Islamic extremist organizations. The work of Tillich, Yalom, May, and others provides the existential lens through which Islamic doctrines and practices, both mainstream and extremist, are examined.