As an Islamo-Arabic utterance,throughout the history of Islam, “Allahu Akbar” has been widely used as one of the most influential religious slogans since the advent of Islam in the 7th century CE. However, during the last four decades, it has gained a fairly global reputation thanks to various functions it has pragmatically come to serve in different social settings. Recently, it has been particularly assigned a world-wide notoriety due to the terrorist acts by extremist Islamist factions. This study aimed at identifying the social, political, and religious contexts in which contemporary Muslims recite “Allahu Akbar” with various pragmatic meanings in mind, making a special distinction between ordinary, peaceful contexts of use and violent contexts, where, in the latter, it is mostly heard from the mouths of extremist factions like ISIS, who, as well, associate themselves with Islam. We have, finally, identified eleven pragmatic functions the utterance serves in today’s Islamic societies, with a special focus on the Iranian context.