Religion: Secret Religion is part of the Macmillan Interdisciplinary Handbooks series dedicated to the study of religion. Composed of twenty-four thematic chapters, this volume looks at the margins of religion or religious texts and traditions that are not considered authoritative by orthodox communities. The volume is broken down into three sections that correspond with different classifications of religion in the margins: gnosticism, with its focuses on knowledge of a transcendent God who is the source of life and the human spirit; esotericism, with its focus on private religion kept from the public and critical of orthodoxy; and mysticism, with its focus on immediate contact with the ultimate reality. Each classification will be explored historically and comparatively to give the reader a more rounded understanding. The volume also includes bibliographies, filmographies, images, a glossary, and a comprehensive index, all of which aid the reader in exploring this rich, rewarding, and relevant field.