To correctly chart the milestones of anti-religious propaganda in accordance with local conditions, some preliminary research work needs to be done. The author, who set himself the task of writing the experience of an anti-religious book on a local history basis, faces a number of questions. It is necessary to reveal the roots of the religiosity of various national groups, to explain the origin of certain religious beliefs in connection with the economy of the region and the class system, to show the same nature with "paganism" and militant Orthodoxy, and Muslims brought to the Volga by Arab merchants. On the one hand, it is necessary to give a historical Marxist essay on such phenomena as Orthodox missionary work, on the other hand, to outline the current state of religious movements: a partial relapse of paganism, the crisis of Orthodoxy, Muslim reformism, and the latest forms of sectarian propaganda. This book has to be considered only as the first attempt to work from this angle of view.