This book is aimed at making the Polish reader more familiar with the contemporary debates on secularism understood as a political regime in which the state remains neutral towards religion(s). Due to the undermining of the so-called secularization thesis – which says that there is a strict connection between the emergence of the modern society and the processes of the privatization or retreat of religion – problems related to religious faith have become particularly pressing these days. The contributions to this volume, authored by prominent philosophers and historians of ideas – among them Charles Taylor and Jonathan Israel – have been divided into two main parts: Secularism in Recent Political Philosophy and Enlightenment and the Birth of the ‘Secular Age’. The first part of the book deals with the problem of religion in the public sphere against the background of an axiologically diversified culture, as well as with the universality of secularism and religious toleration. The second part comprises texts which bear on the historical roots of secularism, in particular the changes in the conception of religion originating in the Enlightenment era. The interdisciplinary character of the contributed chapters shows that secularism and the related conceptions of religion constitute extremely complex issues, underlain by a variety of historical processes, such as the ermergence of a secular anthropology or the Enlightenment attempts at rationalizing religion.