An article that pretends to be objective but reflects a Protestant understanding of Catholic:
Catholic - derived, through Latin, from the Greek adjective καθολικός, meaning "general", "universal" (cf. Henry George Liddell, Robert Scott, A Greek-English Lexicon)
In common parlance the term most often refers to the members, beliefs, and practices of the Catholic Church (Roman Catholic Church) that is in full communion with the Pope (Bishop of Rome). It comprises the Latin Rite and twenty-two Eastern Rite Catholic Churches. The Eastern Catholic particular Churches include the Ukrainian, Greek, Greek Melkite, Maronite, Ruthenian Byzantine, Coptic Catholic, Syro-Malabar, Syro-Malankara, Chaldean, and Ethiopic Rites.
The Eastern Orthodox Church also identifies as Catholic, as in the title of The Longer Catechism of the Orthodox, Catholic, Eastern Church.
Most Reformation and post-Reformation Churches use the term Catholic (sometimes with a lower-case c) to refer to the belief that all Christians are part of one Church, regardless of denominational divisions. It is in line with this interpretation, which applies the word "catholic"/"universal" to no one denomination, that they understand the phrase "One Holy Catholic and Apostolic Church" in the Nicene Creed, the phrase "the catholic faith" in the Athanasian Creed, and the phrase "holy catholic church" in the Apostles' Creed.
The term is used also to mean those Christian Churches which maintain that their Episcopate can be traced unbrokenly back to the Apostles, and consider themselves part of a broad catholic (or universal) body of believers. Among those who regard themselves as "Catholic", but not "Roman Catholic" , are Anglicans, and some small groups such as the Old Catholic Church, the Polish National Catholic Church, the Independent Catholic, the Ancient Catholic and Liberal Catholic Churches, as well as Lutherans (though the latter prefer the lower-case "c," and, like Anglicans, stress that they are both Protestant and Catholic).
The term can refer to the one Church founded by Jesus through the Apostle Peter, according to Matthew 16:18-19: "And I tell you, you are כיפא (Kepha) (Aramaic for "rock"), and on this rock I will build my Church, and the powers of death shall not prevail against it. I will give you the keys of the kingdom of heaven, and whatever you bind on earth shall be bound in heaven, and whatever you loose on earth shall be loosed in heaven.’" In Roman Catholic theology, this is understood to mean specifically the Roman Catholic Church.
Some use the term Catholic to distinguish their own position from a Calvinist or Puritan form of Reformed-Protestantism. These include High Church Anglicans, known also as "Anglo-Catholics", 19th century Neo-Lutherans, 20th century High Church Lutherans or evangelical-catholics and others.
Methodists and Presbyterians believe their denominations owe their origins to the Apostles and the early Church, but do not claim descent from ancient Church structures such as the episcopate. Neither of these Churches, however, denies that they are a part of the catholic (universal) Church.
History of usage
A letter that Saint Ignatius wrote to Christians in Smyrna  in about 107 is the earliest surviving witness to the use of the term "catholic Church" (Smyrnaeans, 8). By it Saint Ignatius designated the Christian Church in its universal aspect, excluding heretics, such as those who disavow "the Eucharist to be the flesh of our Saviour Jesus Christ,which suffered for our sins, and which the Father, of His goodness, raised up again" (Smyrnaeans, 7). He called such people "beasts in the shape of men, whom you must not only not receive, but, if it be possible, not even meet with" (Smyrnaeans, 4). The term is also used in the Martyrdom of Polycarp in A.D. 155 and in the Muratorian fragment, about A.D. 177.
St Cyril of Jerusalem (circa 315-386) urged those he was instructing in the Christian faith: "If ever thou art sojourning in cities, inquire not simply where the Lord's House is (for the other sects of the profane also attempt to call their own dens houses of the Lord), nor merely where the Church is, but where is the Catholic Church. For this is the peculiar name of this Holy Church, the mother of us all, which is the spouse of our Lord Jesus Christ, the Only-begotten Son of God" (Catechetical Lectures, XVIII, 26).
The term "Catholic Christians" entered Roman Imperial law when Emperor Theodosius defined its followers as adherents that "...should continue the profession of that religion which was delivered to the Romans by the divine Apostle Peter, as it has been preserved by faithful tradition and which is now professed by the Pontiff (Pope) Damasus..."; "...but as for the others, since in our judgement they are foolish madmen, we decree that they shall be branded with the ignominious name of heretics, and shall not presume to give their conventicles the name of churches." This law was enacted in Thessalonica and published in Constantinople on 27 February AD 380 and forms part of the Codex Theodosiani Liber Decimus Sextus, De Fide Catolica — The Catholic Faith. This established Catholic Christianity as the official religion of the Roman Empire.
The use of the term "Catholic" to distinguish the "true" Church from heretical groups is found also in Saint Augustine, who wrote:
"In the Catholic Church, there are many other things which most justly keep me in her bosom. The consent of peoples and nations keeps me in the Church; so does her authority, inaugurated by miracles, nourished by hope, enlarged by love, established by age. The succession of priests keeps me, beginning from the very seat of the Apostle Peter, to whom the Lord, after His resurrection, gave it in charge to feed His sheep (Jn 21:15-19), down to the present episcopate.
"And so, lastly, does the very name of Catholic, which, not without reason, amid so many heresies, the Church has thus retained; so that, though all heretics wish to be called Catholics, yet when a stranger asks where the Catholic Church meets, no heretic will venture to point to his own chapel or house.
"Such then in number and importance are the precious ties belonging to the Christian name which keep a believer in the Catholic Church, as it is right they should ... With you, where there is none of these things to attract or keep me... No one shall move me from the faith which binds my mind with ties so many and so strong to the Christian religion... For my part, I should not believe the gospel except as moved by the authority of the Catholic Church.
St. Augustine (354–430): Against the Epistle of Manichaeus called Fundamental, chapter 4: Proofs of the Catholic Faith.
A contemporary of Augustine, St. Vincent of Lerins, wrote in 434 under the pseudonym Peregrinus a work known as the Commonitoria ("Memoranda"). While insisting that, like the human body, Church doctrine develops while truly keeping its identity (sections 54-59, chapter XXIII), he stated: "[I]n the Catholic Church itself, all possible care must be taken, that we hold that faith which has been believed everywhere, always, by all. For that is truly and in the strictest sense 'Catholic,' which, as the name itself and the reason of the thing declare, comprehends all universally. This rule we shall observe if we follow universality, antiquity, consent. We shall follow universality if we confess that one faith to be true, which the whole Church throughout the world confesses; antiquity, if we in no wise depart from those interpretations which it is manifest were notoriously held by our holy ancestors and fathers; consent, in like manner, if in antiquity itself we adhere to the consentient definitions and determinations of all, or at the least of almost all priests and doctors" (section 6, end of chapter II).
The term "Catholic Church" is normally associated with the Church that is led by the Roman Pontiff, currently Pope Benedict XVI, and whose over one billion adherents are about half of the estimated 2.2 billion Christians. Other Christian denominations also lay claim to the description "catholic", including the Eastern Orthodox Church and those Protestant Churches possessing the historic episcopate (bishops).
In some countries, Catholic is included in the official name of a particular parish church, school, hospice or other institution belonging to the Roman Catholic Church, to distinguish it from those of other denominations. For example, the name "St. Mark's Catholic Church" seeks to make clear that it is not an Anglican or Lutheran church. In other countries, such as England, it would be more usual to use "Roman Catholic Church" in this context.
Many of those who apply the term "Catholic Church" to all Christians indiscriminately object to this use of the term to designate what they view as only one denomination within what they see as the "whole" Catholic Church. However, the Roman Catholic Church considers itself to be the Catholic Church, with others as "non-Catholics", and regularly refers to itself as the Catholic Church. This practice is in application of the belief that not all who claim to be Christians are part of the Catholic Church - a belief that goes back to Saint Ignatius of Antioch, the earliest known writer to use the term Catholic Church - and that communion with the Roman Pontiff is essential for membership.
Though normally distinguishing itself from other Churches by calling itself the Catholic Church, it accepts the description "Roman Catholic Church" in its relations with some of them. Even outside documents drawn up jointly with these Churches, it has sometimes, in view of the central position it attributes to the See of Rome, adopted the adjective "Roman", as in the papal encyclicals Divini illius Magistri and Humani generis. Another example is its self-description as the "Holy, Catholic, Apostolic and Roman Church" in the 24 April 1870 Dogmatic Constitution on the Catholic Faith of the First Vatican Council. In all of these documents it refers to itself also simply as the Catholic Church.
As noted, in addition to the Roman Catholic Church, the Eastern Orthodox Church, Oriental Orthodoxy, and the Assyrian Church of the East all see themselves as the "one holy catholic and apostolic Church" of the Nicene Creed. Anglicans and Old-Catholics each see themselves as a Communion within that one Church, and Lutherans see themselves as "a reform movement within the greater Church catholic." The Orthodox do not recognize the universal primacy of the Bishop of Rome (i.e., the Pope), but do rank him as primus inter pares ("first among equals") among the five major ancient Christian Patriarchates (super-metropolitical archiepiscopal Sees) of Constantinople, Alexandria, Jerusalem, Antioch, and Rome. Anglicans and Old-Catholics accept that the Bishop of Rome is primus inter pares among all primates, but they embrace Conciliarism as a necessary check on what they consider to be the "excesses" of Roman Ultramontanism. The Catholic Church's view of the Bishop of Rome is that he is not only primus inter pares, but that he is also given a special charism as the "Successor of Peter" to serve as universal pastor to the entire Church. The Catholic Church summarizes this view with the ancient quote, "Where Peter is, there is the Church."
Roman Catholics, Orthodox Christians (in general), and the Assyrian Church of the East each recognize the "validity" of each other's Eucharist (Mass or Divine Liturgy), and of the holy orders of their respective priesthoods and episcopate. The Roman Catholic Church, on the other hand, considers Anglican Holy Orders to be "null and void," as declared by Pope Leo XIII in his Bull Apostolicae curae. Beginning with the Encyclical Letter Saepius officio of the Archbishops of Canterbury and York in response to Apostolicae curae, Anglicans, for obvious reasons, have steadfastly rejected this claim. At present, Old-Catholics are in full communion with the worldwide Anglican Communion, including full exchange of clergy and participation in each other's ordinations (including episcopal consecrations), and many Lutheran Churches are in communion with Anglican provinces. Although there were several statements made by a couple of Orthodox leaders in the early 20th century giving hope to High Anglican clergy that their priestly orders would eventually be recognized as valid by the Orthodox, today there is little variance among Orthodox patriarchs and metropolitans on the validity of Anglican Orders. As with the Catholic Church, today the Orthodox churches universally require ordination to the priesthood for Anglican clergy that convert to Orthodoxy, evidencing the prevailing Orthodox view that the Anglican liturgy is non-sacramental in nature. Recent decisions by various Anglican/Episcopal bishops to ordain women to the priesthood and to the episcopate have rendered any hope of formal ecclesiastical union with Orthodoxy (from the Orthodox point of view) a moot point.
Thus, for example, in an emergency, when no Roman Catholic priest is available, a Roman Catholic may, under canon law, receive the Holy Eucharist and receive absolution from an Orthodox priest, but not from an Anglican priest. This also means that if an Episcopal or Anglican male priest converts to the Roman Catholic Church, the Roman Catholic Church confers ordination on him (in its view, for the first time) and excludes women from Holy Orders. This divergence of belief is a considerable block to greater unity, in spite of substantial progress in ecumenical dialogues between Anglicans and Roman Catholics since the Second Vatican Council.
Recent historic ecumenical efforts on the part of Roman Catholic Church have focused on healing the rupture between the Western ("Latin" or "Catholic") Christian Church and the main body of the Eastern ("Greek" or "Orthodox") Christian Church. Before he was incapacitated with a degenerative illness, Pope John Paul II often spoke of his great desire that the Catholic Church "once again breathe with both lungs," thus emphasizing that the Catholic Church seeks to restore full communion with the separated "Eastern" and "Oriental" Christian Churches.
After the first rupture in the Catholic Church in 1054 between East and West, a brief reunification took place in the mid-15th century at the Council of Florence. The present Pope (Benedict XVI) has stated his intentions in restoring full unity with the Orthodox. From the Catholic standpoint, almost all of the ancient theological differences have been satisfactorily addressed (the Filioque clause, the nature of purgatory, etc.), and the experience of the Eastern Catholic Churches in communion with Rome has shown that the eventual reunion will not mean a "Latinization" of the Eastern Churches.
Avoidance of usage
Some Protestant Churches avoid using the term completely, to the extent among many Lutherans of reciting the Creed with the word "Christian" in place of "Catholic".    The Orthodox Churches share some of the concerns about Roman Catholic papal claims, but disagree with some Protestants about the nature of the Church as one body. For some, to use the word "Catholic" at all is to appear to give credence to papal claims.