The subject of Church History (or History of Christianity) is the third discipline within the classical disciplines of Protestant theology, alongside the subjects of Old and New Testament, whose object of research is Christianity in its historical manifestations of the past two millennia. It encompasses the community of interpretation and tradition founded in the biblical tradition, as well as the plurality of institutional churches and movements, and furthermore the secular forms of impact and transformation of the Christian religion that are to be distinguished from them.

In their research methods and working methods, church historians do not differ from the methodology of general historiography. Nevertheless, the subject is not a special discipline of historical science, but an independent theological discipline within the canon of theology, whose findings are necessary "in order to be able to understand Christianity as a magnitude that has become historical" (Christian Hornung). With its research, church history opens up access to the cultural memory shaped by Christianity, in which one's own life world participates. At the same time, it invites us to "remember", i.e. to go in search of traces of faith, of failures, but also of the hopes and ethical responsibility of past generations, in order to gain new perspectives for our own present.

The subject of church history at the University of Oldenburg is characterised by a consistent ecumenical perspective in research and teaching. In addition, students are taught intercultural and postcolonial approaches to topics in non-European Christian history in regular events. Other important aspects of teaching and research in church history are, on the one hand, the constant exchange with other theological disciplines and, on the other hand, the trans- and interdisciplinary networking with other disciplines, e.g. with general history, art and music history as well as Jewish studies.