In the New Testament period, there were no denominations, and the phrase "the church" refers either to all who follow Jesus, or all who follow Jesus in a particular location. As Christianity has divided, some groups or denominations have claimed that they alone represent "the one and only church" to which Jesus gave his authority. Other denominations believe that "the church" includes members of many denominations, believing in "an invisible church". A similar theory arose in the 4th and 5th centuries, present in Novatianism and Donatism— both of which were condemned by the mainstream Church of their time.

Apostolic succession is sometimes seen as one of the essential elements in constituting the one true church, ensuring it has inherited the spiritual, ecclesiastical and sacramental authority and responsibility that Jesus Christ gave to the Apostles. Other denominations believe they have restored the original church, in belief or practice. The claim to be the one true church is related to the first of the Four Marks of the Church mentioned in the Nicene Creed: "one, holy, catholic, and apostolic church".

True may refer to: