The Roman Catholic Church specifically

An invisible body of believers from all over the world from the beginning of Act 15 up to now who are either on Earth or Heaven, believers are defined as those who have accepted Jesus Christ as their own personal Lord and Saviour.

Unitarian Universalism

Ecumenism (also oecumenism, œcumenism) refers to initiatives aimed at greater religious unity or cooperation. Most commonly, ecumenism is used in its narrow meaning, referring to greater co-operation among different Christian groups or denominations....

A translation of catholic as in "catholic church".

Universalism is a religion and theology that generally holds all persons and creatures are related to God or the divine and will be reconciled to God. A church that calls itself Universalist may emphasize the universal principles of most religions and...

The idea that all Christian churches and sects share certain things in common

The idea that all Christians form part of a single body. This idea had more organisational force in pre-Reformation Western Europe, when the Roman Catholic Church dominated the local religious landscape. Note that the original etymological form of the word catholic meant "universal".

Part of one of the titles of the Pope, the bishop of Rome: The Supreme Pontiff of the Universal Church.

The precise definition of what constitutes a Christian, though intrinsic to these distinctions, often remains a matter for dispute. Historian Arnold J. Toynbee, in the seventh volume of his 1961 A Study of History, discoursed at length on both the creation of universal churches by the internal proletariats of failing civilizations and their important role as a "chrysalis" in the formation and nascent health of succeeding apparented civilizations. (For example, the Roman Catholic Church was formed by the disaffected subjects of the decaying Hellenic civilization under the oppressive universal state of the Roman Empire, and served as the foundation for the subsequent Western Civilization.) Toynbee noted that the failure of the creative elite of a civilization to meet present challenges leads to the breakdown of universal mimesis by which a society remains coherent and cooperative. This then presages the division of a civilization into a dominant but uncreative minority increasingly obsessed by power, technique and management; and both internal and external proletariats of the disaffected. The conflict between these parties can if unresolved lead to civilizational collapse and dissolution -- with the dominant minority creating a universal state or empire; the external proletariat creating barbarian war-bands in response; and the internal proletariat creating a universal church.