Ecclesiology usually refers to the theological study of the Christian Church. However, when the word was coined in England in the early 1840s, it was defined as the science of the building and decoration of church buildings and it is still, though rarely, used in this sense.

In its theological sense, ecclesiology deals with the origins of Christianity, its relationship to Jesus, its role in salvation, its polity, its discipline, its destiny, and its leadership. Since different ecclesiologies give shape to very different institutions, the word may also refer to a particular church or denomination’s character, self-described or otherwise – hence phrases such as Roman Catholic ecclesiology, Lutheran ecclesiology, and ecumenical ecclesiology.