The expression "one true church" refers to an ecclesiological position asserting that Jesus gave his authority in the Great Commission solely to a particular visible Christian institutional church—what is commonly called a denomination. This view is maintained by the Catholic Church, the Eastern Orthodox Church, the Oriental Orthodox communion, the Assyrian Church of the East, the Ancient Church of the East, the Christian Churches/Churches of Christ, the Churches of Christ, and the Lutheran churches, as well as certain Baptists. Each of them maintains that their own specific institutional church (denomination) exclusively represents the one and only original church. The claim to the title of the "one true church" relates to the first of the Four Marks of the Church mentioned in the Nicene Creed: "one, holy, catholic, and apostolic church". As such, it also relates to claims of both catholicity and apostolic succession: asserting inheritance of the spiritual, ecclesiastical and sacramental authority and responsibility that Jesus Christ gave to the apostles.

A Christian denomination is a distinct religious body within Christianity that comprises all church congregations of the same kind, identifiable by traits such as a name, particular history, organization, leadership, theological doctrine, worship style and, sometimes, a founder. It is a secular and neutral term, generally used to denote any established Christian church. Unlike a cult or sect, a denomination is usually seen as part of the Christian religious mainstream. Most Christian denominations refer to themselves as churches, whereas some newer ones tend to interchangeably use the terms churches, assemblies, fellowships, etc. Divisions between one group and another are defined by authority and doctrine; issues such as the nature of Jesus, the authority of apostolic succession, biblical hermeneutics, theology, ecclesiology, eschatology, and papal primacy may separate one denomination from another. Groups of denominations—often sharing broadly similar beliefs, practices, and historical ties—are sometimes known as "branches of Christianity". These branches differ in many ways, especially through differences in practices and belief.