The main themes and topics covered in "Demon Possession and Allied Themes" include:Demon Possession: Nevius discusses the belief in demon possession, which was prevalent in certain cultures and societies he encountered during his missionary work. He explores the manifestations of alleged demonic possession, the symptoms displayed by those believed to be possessed, and the methods used for exorcism.Exorcism and Spiritual Warfare: The book delves into the practices and rituals used for exorcism, focusing on how missionaries and local practitioners sought to address cases of possession through prayer and spiritual warfare.Spiritualism and Mediumship: Nevius also examines other supernatural phenomena, such as spiritualism and mediumship, which were of interest during the 19th century. He discusses how these practices were perceived and responded to by both missionaries and the local population.Comparative Religions: In his work, Nevius draws comparisons between the beliefs and practices related to demon possession and spiritual phenomena in various cultures, seeking to understand their similarities and differences.Theological Perspectives: Throughout the book, Nevius offers his theological reflections on the nature of evil, the power of demonic forces, and the role of Christianity in confronting these spiritual challenges.