This book argues that the common notion of a fundamental conflict between the secular and the religious cannot be applied to Islam. This is not because Islam rejects the secular in favor of the religious; it is because Islam’s concept of the religious includes the secular. This is what is captured by the term “Islamic Secular.” Contrary both to the notion that “religion” in Islam equals “sharī‘ah,” and to the concomitant notion that sharī‘ah is the all-encompassing, exclusive metric of assessment in Islam, this book argues that, while Islam is all-encompassing, sharī‘ah is bounded. This leaves a space between the limited circumference of sharī‘ah and the unlimited circumference of Islam. While both spaces are “religious” in that they come under the adjudicative gaze of the God of Islam, only the shar‘ī space draws directly upon sharī‘ah and its sources, while the non-shar‘ī space does not. In the end, this allows for a “religious secular,” a space wherein matters remain “religious” but their concrete substance is neither based on nor assessed in terms of sharī‘ah or its sources. These shar‘ī and non-shar‘ī elements are not rivals but complements. As such, both “secularism” and “secularization,” as non- or anti-religious tropes, are alien to the Islamic Secular.