Roman Catholic is a term sometimes used to differentiate members of the Catholic Church in full communion with the Pope (of the See of Rome) from other Christians, especially those who also self-identify as “Catholic”. “Catholic” is one of the Four Marks of the Church set out in the Nicene Creed, a statement of belief accepted by members of many denominations some of which assert belief in an invisible form of “Christian Church” analogous to branch theory and Protestant ecclesiology. Branch theory would believe in an invisible Christian Churchstructure binding various Christian denominations together whether in formal communion or not.
While the term “Roman”, as in the “Roman Church”, has been attested since the Middle Ages – often connoting the local particular church of the Diocese of Rome – the first known occurrence of “Roman Catholic” as a synonym for “Catholic Church” was in communication with the Armenian Apostolic Church in 1208, after the East–West Schism.
Following the pejorative term “papist”, attested in English since 1534,the terms “Popish Catholic” and “Romish Catholic” came into use during the Protestant Reformation. During the 17th century, “Roman Catholic Church” was often used as a synonym for the Catholic Church, especially where Protestants and Anglicans dominated demographically. Although its usage has since changed over the centuries, the name continued to be widely used in English-speaking countries,including the United States.
By 1900, U.S. Catholics numbered 12 million, with a predominantly Irish clergy.Accordingly, they had an arguably more influential voice than the recusants in the United Kingdom, and objected to what they considered the reproachful terms “Popish” and “Romish”, preferring the term “Roman Catholic” rather than the former.
Formulations such as the “Holy Roman Church” or the “Roman Catholic Church” were sometimes used by officials of the Catholic Church before and after the Reformation, especially in the context of ecumenical dialogue where the dialogue partner had a reason to prefer this usage.
The use of “Catholic Church” is usually preferred by the Holy See and most of its adherents. The last official magisterium document to use “Roman Catholic Church” was issued by Pope Pius XII in 1950.”Catholic Church” was used by Pope Paul VI when signing the documents of the Second Vatican Council.This preference also usually appears on the website of the Holy See. In the Catechism of the Catholic Church, only “Catholic Church” is used. This use is also broadly reflected in academia, as well as in most English-language media. Change in Catholic usage since 1950 may reflect that the majority of Catholics live outside the Western world and the Catholic church is more truly a world church. When “Roman Catholic” is used today it often indicates that a local church uses Latin, the language long favored by the Holy See in Rome, in its liturgy.