The Orthodox Church keeps the original Nicene Creed, accepted by the Universal Church, East and West, during the first millennium without the addition of "And the Son" or the "Filioque." It accepts, on faith, Christ's words in the Gospel, that the Father is the Unoriginate Source of the Life of the Trinity, with the Only-Begotten Son and the Holy Spirit Proceeding from the Father Alone. We cannot know how the Begetting of the Son and the Proceeding of the Spirit from the same Father is different, only that it is and this distinguishes the two Persons.

The West decided to add "And the Son" which is a philosophical conclusion, without warrant, in fact, in Scripture or the Fathers. It was not so much Orthodox Rome that adopted the addition to the Creed, as it was the Frankish theologians of Charlemagne, individuals who were hardly in the grand tradition of Orthodox Theology in both East and West.

This addition to the Creed in the West led to the eventual break between the two Churches beginning in 1054 and solidifying finally at the Sack of Constantinople in the thirteenth century by the western Crusaders (really "sword-bearers" rather than "cross-bearers").

Roman Catholic theologians today agree that the addition to Triadic theology of the filioque led to negative consequences in western theologyas a whole.

In general, the role of the Holy Spirit Himself seemed to be downplayed.

The Words of Institution ("This is my Body . . .) became the "consecrating formula" for the Eucharist in the West, while the entire Canon, the anamnesis, the Words of Institution and the Epiclesis of the Holy Spirit remained the "consecrating formula" (it is a bad term, isn't it?) in the East. Those Western Churches which have returned to Orthodoxy have restored the Epiclesis in their liturgies to where it once was.

In addition, the Roman view on Original Sin is different. Following largely Augustine of Hippo, the West believes, although has never declared doctrinal, the view that we somehow inherit the Sin of Adam, and not just the consequences of that sin. The Orthodox Church has always held that Original Sin is about the consequences of Adam's Sin (how can we be responsible for someone else's personal sin?). These consequences are basically death, concupiscence and our tendency toward sin in our nature.

As a result of this view, the West has declared the Mother of God to be Conceived Immaculately, without the Sin of Adam and to have been assumed into Heaven body and soul.

The Orthodox Church has always believed that the Mother of God is the highest person above all humanity and the angels owing to her role as Mother of the Word Incarnate. She believes that the Mother of God was perfectly holy and most holy and sinless. The Church celebrates Our Lady's Nativity, which would be impossible otherwise since only the feasts of Saints may be celebrated.

In Her Prayers, the Orthodox Church praises the Mother of God as "All-Immaculate" and "Most Immaculate" and Most Holy etc. The Orthodox Church believes and celebrates the Dormition and Assumption into Heaven of the Body and Soul of the Mother of God, but has never defined these, since Her Liturgy has always defined them. Indeed "Orthodox" means, at one and the same time, "Right Faith" and "Right Worship." Our worship expresses our faith.

The great devotion to the Holy Spirit in the Orthodox Church has always led it to celebrate the divinization or Theosis of humanity through the Incarnation, Death and Resurrection of our Lord, God and Saviour Jesus Christ Who sends us His Holy Spirit, the Comforter. We are partakers of the Divine Nature, God's Energies through Christ and in the Spirit. This dynamic view of salvation is characteristic of the Orthodox Church, whereas in the West, Christ's death on the Cross has been emphasized to be a kind of "pay-back" to God the Father Who was offended by the sins of humanity. In Eastern Icons, the halo is always part of the body of the saint. In Western saints' pictures, the halo is often disconnected from the body and is above the head - this illustrates different views of salvation by both Churches.

The Orthodox East prays for the faithful departed incessantly so that God may bring them closer to Himself. The West has defined a place called purgatory where the souls of those with small sins or debts must suffer again to "pay back" to God what they "owe." Legalism is therefore a hall-mark of the Roman Church as well. It is unknown in the East, as are indulgences.

Then there are the doctrines surrounding papal primacy. The Orthodox Church believed that the Pope of Rome was "first among equals" in a grouping of patriarchs of the universal Church when sitting in Council. In addition to this, the popes of later centuries declared a primacy of jurisdiction for themselves and infallibility when defining doctrine from the Chair of Peter.

The Orthodox Church has always held Ecumenical Councils as the highest Organ of the Church where doctrine and morals can be codified and defined.

For the Roman Church, the Pope is a kind of "world Bishop" with the world as his diocese as the only Successor of Peter. The Orthodox Church has a truly social and "catholic" or "holistic" view which is also Her theology of the Eucharist, that the fullness of the Church is present in each of Her parts throughout the world, wherever it is organized around the episcopate, the successors of Peter and the Apostles, with the sacraments/mysteries and the fullness of the Orthodox Catholic Christian Faith handed down from them as well.

It should be noted that Rome in the West was the only city where the Apostles Peter and Paul preached and established a Church. Thus, Rome became the West's Apostolic See because it was the only one. In the East, Peter and Paul and the Apostles established churches in many cities, such as Antioch, and in many villages and towns so that deference to any one on the basis of Apostolicity would have been impossible.

This is why the Orthodox Church finds the claims of Rome rather strange given that she has always had the Apostles as Her pillars and founders from Her very beginning. Rome's claims are, in actual fact, based more on its position as the capital of the ancient Roman Empire, a position that shifted to Constantinople, the New Rome, later. The Orthodox Patriarchate of Jerusalem comes from the Apostolic Age, as do the Patriarchates of Alexandria and Antioch. The Orthodox Church is the earliest Church of the Apostles.