"catholic" (Catholics) actually means "universal". It was an attempt to weld the thousands of Christian cults into one religion. Why certain Churches call themselves "Catholic" is - well, because they choose to. None is actually universal.
The word "catholic" by itself simply means "all." But, the "Catholic" Church is a different thing. "Catholic" churches are those coming under the Bishop of Rome, the Pope. Roman Catholics are the biggest grouping, but there are others, like the Ukrainian Catholics, and so on. As Nicea and the early councils happened before the Great Schism of 1054 (before the Catholic church existed) the denominations after this typically accept these councils. This is true of the Orthodox, Catholic, and many Protestant churches, e.g., the Anglicans (who accept 7 councils if memory serves).
As an Anglican, I pray for the "Holy catholic and apostolic church" as is found in the Creed. Anglicans consider their denominations "catholic, and reformed," but definitely not in the "Catholic" side of things.
Catholic is a descended adjective from the Greek adjective ?????????? / Catholics? Which in turn means general; universal.
Among other places, in the concluding verses of the Gospel of St. Matthew (28, 19-20), and St. Mark (16, 15-16): ?Go into the whole world and preach the gospel to every creature. He who believes and is baptized shall be saved, but he who does not believe shall be condemned.?
Compare St. John, 10, 16: ?And other sheep I have that are not of this fold. Them also I must bring, and they shall hear my voice, and there shall be one fold and one shepherd.?
Of course the name ?Catholic? was not given to the Church of Christ until after the time of the New Testament. It was commonly called merely ?The Church? or ?Holy Church. ? There was no need to distinguish. There was only one Church.
St. Ignatius seems to have been the first to give the name ?Catholic? to ?The Church.? He did this in a letter he wrote about the year 107, and in the course of the next two centuries the name caught on, and came into general use. By that time there were a few heresies in vogue, like Arianism, and "Catholic" became a name to distinguish the true Church from error and schism.
In the beginning the word ?catholic? was simply an adjective meaning ?universal.? Then it came to have the meaning of "one and only" and to be used as an appellate?a ?proper name? for the Church. This appellatevESE did not become common until the fourth century.
The Apostles Creed in the beginning had ?I believe in the Holy Church.? The word ?Catholic? was inserted in the fourth century. Some Protestants have now thrown this word ?Catholic? out of the Creed and frankly substituted the word ?Christian.?
As for the word ?Roman,? that is an Anglicanism?considered superfluous by all continental Europeans. It is like calling a man by his confirmation name, in addition to his baptismal and family names.
The word ?Roman Catholic? really came from the legislative enactments of Protestant England. They tried to pretend that there was another ?Catholic? Church, namely, the ?English Catholic.? Hence the name "Roman" was needed to distinguish the two. We still employ the consequences of their fiction.
The Holy Orthodox Catholic and Apostolic Church and the Roman Catholic Church were one Church - the Catholic Church - for over 1,000 years. Common to both are most of the points of the Nicene Creed (http://www.goarch.org/chapel/liturgical_texts/creed).
* belief in the Holy Trinity - Father, Son and Holy Spirit
* the crucifixion and resurrection of Christ
* the future return of Christ and his everlasting kingdom
Similar also are
* liturgical worship
* the seven major sacraments (Orthodoxy recognizes more)
* the change of communion bread and wine into the body and blood of our Lord Jesus Christ
* baptism in the name of the Father, Son, and Holy Spirit
* male clergy consisting of bishops, priests, and deacons
The chief differences which caused the split between Orthodox Christianity and Roman Catholicism:
Orthodoxy believes
* the Holy Spirit proceeds from the Father (Nicene Creed and John 15:26)
* the regional churches are united by meetings of their chief bishops, with no ruling bishop over all.
Roman Catholicism believes
* the Holy Spirit proceeds from the Father "and the Son" (a Roman addition to the Creed)
* the Pope of Rome should be the presiding bishop over all Christianity
Later dogmas that are required for Roman Catholics to believe, but are not Orthodox dogmas:
* purgatory
* infallibility of the Pope
* the immaculate conception of Mary
according to the term catholic, the orthodox eastern churches and the roman church an
