While in the last decade the number of Islamist terrorist attacks in Europe was very small, post-9/11, small violent Islamist cells caused and aim at mass casualties. While autonomous and self-generating, they pursue transnational agenda, blurring the distinction between internal and external security, and are viewed by European states and agencies as the most serious terrorist threat, in terms of its destabilizing political effects. Terrorism, however, is hardly the main manifestation of Muslim radicalization in Europe—a process that takes many forms and may be more likely to transform to peaceful protest and forms of violence other than terrorism, ranging from delinquency, vandalism and hate crimes in “failed suburbs” to public disorders and riots. Any links between religious awakening and socio-political radicalization of Muslim youth in Europe and the rise of Islamist terrorism should be treated with caution and are mostly indirect and non-binding: while the main age category for Islamist terrorism suspects is young adults, Muslims are generally younger in Europe than the rest of the population; younger people are deeper affected by moral outrage at the “injustices” against Muslims at levels from local to global and more likely to seek glory through direct violent action.