This refers to the orthodox churches and those sharing the spiritual and cultural ethos which derives from the Byzantine Empire.
There are over 214 million Orthodox Christians today.
There are four ancient patriarchates, which have special positions of honour and authority: Alexandria, Antioch, Jerusalem and Constantinople.
The churches extend across Eastern Europe, Slav countries and the eastern Mediterranean.
The split with the western church came about because of conflict over the Pope's claim to supreme authority and a clause added to the church's creed which said that the Holy Spirit came from the Son of God as well as God.
Veneration of icons is an important part of public and private worship.
Monastries have played an important part in the history of the church. Mount Athos in Greece has been the chief monastic centre since the 10th century
The Roman Catholic Church
It is the largest of the Christian denominations, with approaching a billion members.
Its origins are from the Western church of the Middle Ages.
It believes in the primacy and authority of the Bishop of Rome (the Pope), who is traditionally regarded as Christ's representative on earth and the successor of St Peter (one of Jesus' disciples and the first Bishop of Rome).
When defining matters of faith or morals what the Pope says is regarded as infallible and binding on all Catholics.
The Second Vatican Council (1962-65) introduced wide reforms and a more open relationship with non-catholic churches.
Both the Roman Catholic and Orthodox churches recognise the 7 sacraments: baptism, confirmation, marriage, ordination, penance (sacrament of reconciliation), extreme unction (anointing the sick) and the Mass.
They rose out of protest against Roman Catholicism in the 16th century.
There are approx. 500 million members.
The contentious issues at the Reformation were the authority of the Pope, the authority and accessibility of Scripture and precise meaning of the eucharist (the ritual of sharing bread and wine to represent Christ's body and blood, as he did with his disciples the night before his death).
The church rejects the supremacy of the Pope.
Emphasis is placed on the authority of the Bible and the traditions of the early church A believer is saved by the grace of God
The priesthood of all believers.
There are four main strands within the Protestant churches: Anglican/Episcopal, Lutheran, Reformed/Presbyterian and the Free Churches.