This book examines recent forms of secularisation to demonstrate that we are now witnessing a “fourth secularisation”: the autonomy of lifestyles. After introducing two initial secularising movements, from mythos to Logos and from Logos to Christianity, the book sets out how from Max Weber onwards a third movement emerged that practised the autonomy of science. More recently, daily life radicalises Weber’s secularisation and its scope has spread out to include autonomy of individual practices, which has given rise to this fourth iteration. The book outlines these first three forms of secularisation and then analyses the fourth secularisation in depth, identifying its three main dimensions: the de-institutionalisation of the religious lifestyle; the individualisation of faith; and the development of new social forms in the religious field. These areas of religious practice are shown to be multiplying partly as a result of the general aestheticization of society. Individuals, therefore, aspire to personal styles of life with regard to beliefs and the choice of their own religious practices. This book will be of great use to scholars of religious studies, secularisation and the sociology of religion.