This dissertation explores the ways marginalized slaves and orphans came together to create new mission communities in western Tanzania. It shows that slave emancipation was a complex process that involved flight to the missions, public declarations, and certification of emancipation. Former slaves joined missions and their descendants became the first-generation Christians, and some worked as teachers, pastors and catechists. The dissertation centers on multiple language communities brought in juxtaposition by the slave trade, wars, and migrations to examine their involvement in the translation of Christian texts into the Kinyamwezi language. It argues that translation of the New Testament, religious texts and songs was a reciprocal process of Africans and European missionaries teaching each other. In so doing, translation became a stimulus for independent interpretation, as Nyamwezi translators acted as independent intellectuals in shaping an African interpretation of Christianity. In remote areas, far from the centers of mission stations, catechists and teachers helped adherents by translating the Bible and religious texts into their own languages, contributing to the growth of African Christianity. In addition to translation, teachers and catechists administered churches in villages, taught catechism, and prepared the young and adults for baptism and confirmation. They established their own schools, and devised teaching methods and ways of obtaining pupils for instruction. Their families not only provided a model of Christian families but also laid the foundation for African Christianity as children were baptized, attended mission schools and became teachers and catechists, and in some cases, nuns and priests. Furthermore, lay women and wives of the Nyamwezi teachers and catechists taught children in Sunday schools, while others accompanied teachers in villages and launched home-visit campaigns to attract more Nyamwezi women to join Christianity. The dissertation further argues that the growth of African Christianity in villages was not entirely the product of European missionary initiatives, but rather in significant measure the result of African cultural and intellectual creativity. The growth of Christianity in the twenty-century western Tanzania gave rise to the revival movement which spread in missions and villages, attracting Christians and pastors into revivalism. Nevertheless, divergent interpretations on the teachings of salvation, sin, and public confession of sins split Christians in the established mission churches into born-again pastors and Christians who supported revivalism and Christians who opposed the movement. This dissertation shows for the first time that lay Christians dissented from the revival movement, preventing born-again pastors and evangelists from holding services in churches. With growing tensions, some Christians seceded from the mainstream churches to form their own churches and installed their own pastors who worked independently from the control of the established churches.