structural:summarization
Catholic Church

In its Letter on Some Aspects of the Church Understood as Communion, the Congregation for the Doctrine of the Faith stressed the belief that the idea of the universal church as a communion of churches must not be presented as meaning that "every particular Church is a subject complete in itself, and that the universal church is the result of a reciprocal recognition on the part of the particular Churches". It insisted that "the universal Church cannot be conceived as the sum of the particular Churches, or as a federation of particular Churches".

The Catholic Church considers only those in full communion with the Holy See in Rome as Catholics. While recognising the valid episcopates and Eucharist of the Eastern Orthodox Church in most cases, it does not consider Protestant denominations such as Lutheran ones to be genuine churches and so uses the term "ecclesial communities" to refer to them. Because the Catholic Church does not consider these denominations to have valid episcopal orders capable of celebrating a valid Eucharist, it does not classify them as churches "in the proper sense".

The Catholic Church's doctrine of infallibility derives from the belief that the authority Jesus gave Peter as head of the church on earth has been passed on to his successors, the popes. Relevant Bible verses include; "And I tell you that you are Peter, and on this rock I will build my church, and the gates of Hades will not overcome it. I will give you the keys of the kingdom of heaven; whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven."

The Latin and Eastern Catholic Churches together form the "Catholic Church", often called the "Roman Catholic Church", the world's largest single religious body and the largest Christian denomination, as well as its largest Catholic church, comprising over half of all Christians (1.27 billion Christians of 2.1 billion) and nearly one-sixth of the world's population. Richard McBrien would put the proportion even higher, extending it to those who are in communion with the Bishop of Rome only in "degrees". It comprises 24 component " particular Churches " (also called "rites" in the Second Vatican Council 's Decree on the Eastern Catholic Churches and in the Code of Canon Law), all of which acknowledge a primacy of jurisdiction of the Bishop of Rome and are in full communion with the Holy See and each other.

These particular churches or component parts are the Latin Church (which uses a number of different liturgical rites, of which the Roman Rite is by far prevalent) and the 23 Eastern Catholic Churches. Of the latter particular churches, 14 use the Byzantine Rite for their liturgy. Within the universal Church, each "particular church", whether Eastern or Western, is of equal dignity. Finally, in its official documents, the Catholic Church, though made up of several particular churches, "continues to refer to itself as the 'Catholic Church ' " or, less frequently but consistently, as the 'Roman Catholic Church', owing to its essential link with the Bishop of Rome.

Richard McBrien, in his book Catholicism, disagrees with the synonymous use of "Catholic" and "Roman Catholic":

But is 'Catholic' synonymous with 'Roman Catholic'? And is it accurate to refer to the Roman Catholic Church as simply the 'Roman Church'? The answer to both questions is no. The adjective 'Roman' applies more properly to the diocese, or see, of Rome than to the worldwide Communion of Catholic Churches that is in union with the Bishop of Rome. Indeed, it strikes some Catholics as contradictory to call the Church 'Catholic' and 'Roman' at one and the same time. Eastern-rite Catholics, of whom there are more than twenty million, also find the adjective 'Roman' objectionable. In addition to the Latin, or Roman, tradition, there are seven non-Latin, non-Roman ecclesial traditions: Armenian, Byzantine, Coptic, Ethiopian, East Syriac (Chaldean), West Syriac, and Maronite. Each to the Churches with these non-Latin traditions is as Catholic as the Roman Catholic Church. Thus, not all Catholics are Roman Catholic... o be Catholic—whether Roman or non-Roman—in the ecclesiological sense is to be in full communion with the Bishop of Rome and as such to be an integral part of the Catholic Communion of Churches.

McBrien says that, on an official level, what he calls the "Communion of Catholic Churches" always refers to itself as "The Catholic Church". However, counter examples such as seen above of the term "Roman Catholic Church" being used by popes and departments of the Holy See exist. The Latin Archdiocese of Detroit, for example, lists eight Eastern Catholic churches, each with its own bishop, as having one or more parishes in what is also the territory of the Latin archdiocese, yet each is designated as being in "full communion with the Roman Church".