This thesis links theological developments in two eras and contexts of Christian history by exploring how the question of Christian identity is dealt with by a number of Christian writers who are chosen for their representative significance in the two contexts. By this approach, the two eras concerned, early Hellenistic Christianity and modern African Christianity, are treated as belonging together within the one entity of Christian history. In a brief Introduction I attempt to establish the case for the methodological principle stated, and also to indicate its importance for understanding modern African theology in particular. Chapter One examines the intellectual and ideological background against which early Hellenistic Christian self-definition was to develop. The attempt is made to show that it was in response to the intellectual and spiritual forces that operated in the Graeco-Roman world, particularly as these affected the "Pagan" perception of Christianity, that the emergent Christian thought developed. The rest of Part One (Chapters Two to Five) examines the viewpoints and achievements of Tatian, Tartullian, Justin and Clement of Alexandria. The emphasis throughout is on how the career and thought of each writer witnesses and responds to the existence of a Christian identity problem. It was in the process of the clarification of Christian identity that theological concerns were also shaped and defined. Part Two deals with the modern African Christian story. Chapter Six examines the legacy of the modern missionary enterprise from Europe and North America as the background to the issues that have gained prominence on the African theological agenda in the post-missionary Church. The rest of Part Two (Chapters Seven to Ten) examines the contributions of four writers - E. Bolaji Idowu, John Mbiti, Mulago gwa Cikala Musharhamina and Byang Kato - towards the definition of African responses to the encounter of the Christian Gospel with African tradition, and towards the development of an African theology. The Conclusion (Chapter Eleven) attempts to use the achievement of the patristic period studied in Part One to clarify some of the areas of theological concern which may yet need to receive attention from African theologians. The presence of an intellectual anti-Christian polemic in Africa, as in the earlier period, is noted as one indication of the need for African theologians to take even more seriously the question of Christian identity in the modern African context. It is as this is done, that the uniquely African contribution to Christian theology will be made.