Sometime around the fourth century CE, Christianity was widely considered to be concentrated in five primary centers: Alexandria, which is now Egypt; Antioch, which is now Turkey; Constantinople, which is now Istanbul; Jerusalem; and Rome. As Islam grew and competed with some of the these centers, Rome and Constantinople became the main Christian centers and, for political, cultural, linguistic and religious reasons, the powers in Rome and Constantinople formally separated in 1054 CE. Those in Constantinople formed the Eastern Orthodox Church, and those in Rome led the Roman Catholic Church. As a result of this separation, which is also referred to as the Great Schism or East-West Schism, there are some differences between the two churches. Some of the main ones are their views of the Pope, the languages used during their services, their beliefs regarding original sin.
The Pope
One difference between the Eastern Orthodox and Roman Catholics has to do with the recognition of the Pope. Roman Catholics recognize the Pope as infallible in matters of doctrine. Moreover, the Pope has supreme authority over all churches and can, for example, contradict or usurp the power of a lower-ranking church leader, such as a priest, bishop or cardinal. The Eastern Orthodox Church also has various bishops, with one being the highest-ranking bishop. Its highest-ranking bishop, or archbishop, is not considered to be infallible, however, nor does he have supreme authority over all of its congregations.
As people-centered forms of government have become more common, papal authority has extended far less than it previously did. A modern Pope might still advise leaders of countries but has no power to make them act. The governments of predominantly Catholic countries are rarely influenced by the Pope alone and might govern in a way that is not in harmony with the Roman Catholic Church’s teachings.
Language of Church Services
Another difference between the churches that was notable until the mid-20th century was that Roman Catholic services were conducted in Latin, rather than in the predominant languages of the areas where the services were being held. The Eastern Orthodox Church conducted services in native languages from its onset. Since the mid-1960s, however, Roman Catholic services often have been conducted in native languages. Members of Opus Dei, a section within the Roman Catholic Church, have continued to hold services in Latin.
Original Sin
Many complex dogmatic distinctions also have arisen since the churches separated. One is the concept of original sin, which the churches teach as having its roots in Adam’s sins in the Garden of Eden. Both churches believe in the concept of original sin, but they hold it to have different consequences. Still, both hold baptism as the way to cleanse the soul of sin.
The churches diverge in how original sin applies to Mary, the mother of Jesus. Catholics believe that Mary born free of original sin and thus was the appropriate vessel for the Son of God. The Eastern Orthodox Church teaches that Mary was cleansed of original sin when Jesus took form in her.
Other Differences
A few minor differences also can be noted:
Eastern Orthodox Churches often have icons, and Catholic churches have statues.
Catholic priests cannot be married, but Eastern Orthodox priests can be married before ordination.
The Eastern Orthodox Church does not believe in purgatory and does not observe the Stations of the Cross.
The Roman Catholic Eucharist is an unleavened wafer, and the Eastern Orthodox Church uses leavened bread.
Easter and Christmas are calculated differently by the two churches.