Nestorianism is a term used in Christian theology and Church history to refer to several mutually related but doctrinarily distinct sets of teachings. The first meaning of the term is related to the original teachings of Christian theologian Nestorius, who promoted specific doctrines in the fields of Christology and Mariology. The second meaning of the term is much wider, and relates to a set of later theological teachings, that were traditionally labeled as Nestorian, but differ from the teachings of Nestorius in origin, scope and terminology. The Oxford English Dictionary defines Nestorianism as:"The doctrine of Nestorius, Patriarch of Constantinople, by which Christ is asserted to have had distinct human and divine persons."

Christian theology is the theology – the systematic study of the divine and religion – of Christianity and Christian belief and practice. It concentrates primarily upon the texts of the Old Testament and of the New Testament, as well as on Christian tradition. Christian theologians use biblical exegesis, rational analysis and argument. Theologians may undertake the study of Christian theology for a variety of reasons, such as in order to:help them better understand Christian tenets make comparisons between Christianity and other traditions defend Christianity against objections and criticism facilitate reforms in the Christian church assist in the propagation of Christianity draw on the resources of the Christian tradition to address some present situation or perceived need education in Christian philosophy, especially in Neoplatonic philosophy