This book is an interdisciplinary socio-missiological study that explores the conversion dynamics of missionary Christianity approach of conversion and the response of Haya converts in the Lutheran Church, Northwest Tanzania. The book argues that the missionary Christianity approach and methods of conversion were important in that they accelerated social change through modernization and appropriation of western education. Nonetheless, the research has ascertained that the missionary Christianity approach produced mainly dual converts who remained adherents of both Christianity and Haya traditional religion. This suggests the reasons for the inadequacy of the missionary Christianity conversion strategic approach to seriously take cognizance of the Haya religio-cultural spirituality and worldview. The Haya Christians tend to actualize “real” conversion within the Revival Movements and Pentecostal-Charismatic churches’ form of Christianity instead of maintaining loyalty to the doctrine of their mother churches, for this spiritual form of Christianity has to a greater extent demonstrated the ability to attempt to indigenize Christianity among them as, without ignoring modern ways of life, it adresses the Haya religio-cultural spirituality and worldview.