But how hard would it be for the two to settle their differences and enter into full communion? Aren’t the Orthodox just Pre-Vatican II Catholics who don't recognize the Pope? Well, not exactly. While we do share a lot in common, there are some real differences. Much of this difference can be traced back to the Orthodox Church not recognizing the authority of any council held after the split, environments and cultures the two Churches developed in, and the challenges the two faced from others to the faith.
Below is a list of a few differences between the two Churches. This list is in no way exhaustive, and each point has only enough detail to try and highlight the difference. Since the term "Orthodox" covers more than one Church (Greek and Russian for example), the summary of the Orthodox position below may vary slightly from group to group within the Orthodox Church.
The most well known, and possibly most significant disagreement between the Catholic and Orthodox (at least historically) is over the filioque. Filioque is a Latin phrase meaning "and from the Son" that is usually credited with bringing about the East-West Schism.
The First Council of Nicea in 325 AD put together the first version of the Nicene Creed we say each Sunday:
"We believe in the Holy Spirit, the Lord, the giver of life, who proceeds from the Father [and the Son]. With the Father and the Son he is worshipped and glorified. He has spoken through the Prophets."
It's the [and the Son] that broke the East and West apart. A local council in Spain added the phrase to the creed in an attempt to battle the Arian heresy (which claimed Jesus was not fully God). At the a Council at Constantinople in 879, it was declared that the version of the creed without the filioque would be accepted and that no further changes to the Creed would be allowed. But in the west the use of the phrase continued unofficially, scandalizing the Orthodox.
The Catholic Church addresses the issue in the Catechism in paragraph 248:
"At the outset the Eastern tradition expresses the Father's character as first origin of the Spirit. By confessing the Spirit as he "who proceeds from the Father", it affirms that he comes from the Father through the Son. The Western tradition expresses first the consubstantial communion between Father and Son, by saying that the Spirit proceeds from the Father and the Son (filioque ). It says this, "legitimately and with good reason", for the eternal order of the divine persons in their consubstantial communion implies that the Father, as "the principle without principle", is the first origin of the Spirit, but also that as Father of the only Son, he is, with the Son, the single principle from which the Holy Spirit proceeds. This legitimate complementarity, provided it does not become rigid, does not affect the identity of faith in the reality of the same mystery confessed."
So while the Orthodox see use of the filioque by the Catholic Church as heresy, the Catholic Church sees the two positions as really a distinction without difference.
If the number one disagreement between the Churches is the filioque, then the argument over the Papacy is a very close number two. The Catholic Church sees the Pope (the bishop of Rome) as the visible head of the Universal Church; the successor to Peter and Vicar of Christ. And when the Pope speaks ex cathedra, he speaks with the assurance that the Holy Spirit will not allow him to teach error.
The Orthodox, as you can guess, have a bit of a problem with this. They believe that the Pope does have authority; not as the Vicar of Christ but as a Bishop of Rome. Some do recognize that the Bishop of Rome has a special role in the Church, but only one of honor and not of authority. They see the present-day office of Pope as a man-made institution with no basis in the Bible or Tradition.
Use of Reason in Truths of the Faith
The two Churches have a very different understanding when it comes to the role philosophy and reason play in the defining and explaining the Truths of the Faith.
The Catholic Church has seen philosophy as the "handmaid of theology", and has used it often to explore and explain many aspects of the faith. Often it is said that the truth, though in a rough form, can be found outside the Church, but only She can bring it together, purify it, and give it meaning.
The Orthodox Church is not as concerned with reason or philosophy as it pertains to faith. They will use reason or philosophy to help defend or explain a truth if possible, but they will not build on either or use either to explore more deeply any truth. In the Orthodox Church, because faith and reason do not need to be reconciled, no effort is made to. The Orthodox would say that they "believe so as to understand, and not understand so as to believe."
The Marian dogmas of the Immaculate Conception and the Assumption are considered by the Catholic Church as Church dogmas. The Orthodox, who only accept dogma defined at Ecumenical Councils, reject these two but that doesn't mean they don't believe them.
The Orthodox celebrate the Dormition of the Theotokos; the death, resurrection, and glorification of Mary. This feast is very close to the Catholic celebration and understanding of Mary's Assumption. And they also refer to Mary as "Most Immaculate" and "Ever-Immaculate" in their Liturgy, but the idea is slightly different since the two Churches do not understand original sin in the same way (more on this below). Since the Orthodox liturgy gives these titles to Our Lady, they see no need for an Ecumenical Council to proclaim it. And since they don't recognize the authority of the Pope (see above), they do not recognize either as being dogma.
The belief in Purgatory that is held by the Catholic Church is not held by the Orthodox Church. In the Catechism of the Catholic Church, paragraph 1030, we find the Church's understanding of Purgatory:
"All who die in God's grace and friendship, but still imperfectly purified, are indeed assured of their eternal salvation; but after death they undergo purification, so as to achieve the holiness necessary to enter the joy of heaven."
In paragraph 1031 we are told where this doctrine was defined:
"The Church formulated her doctrine of faith on Purgatory especially at the Councils of Florence and Trent. The tradition of the Church, by reference to certain texts of Scripture, speaks of a cleansing fire..."
Again, since the Orthodox do not recognize either of these councils as Ecumenical Councils (though they were present at Florence), they do not see either as authoritative. Instead, the Orthodox believe that after a person dies the soul separates from the body and travels to the "abode of the dead". At the end of time, the soul and body are rejoined and Christ will judge them. Those with God's life in them will enter into the bliss of heaven, those without into the eternal torment of hell.
The Orthodox and Catholic Churches both believe that the fall of Adam and Eve brought with it the consequences of a tendency towards sin (concupiscence) and death. But, where the Catholic Church teaches that we also bear the sin of the fall, or Original sin, the Orthodox do not.
To the Orthodox the "original" part of the sin only speaks of it being the "first" sin committed, and while we share in the consequences, the guilt of that first sin falls with Adam and Eve alone and not passed on to all humans.
The Catholic Catechism in paragraph 404 states:
"How did the sin of Adam become the sin of all his descendants? The whole human race is in Adam "as one body of one man". By this "unity of the human race" all men are implicated in Adam's sin, as all are implicated in Christ's justice. Still, the transmission of original sin is a mystery that we cannot fully understand. But we do know by Revelation that Adam had received original holiness and justice not for himself alone, but for all human nature. By yielding to the tempter, Adam and Eve committed a personal sin, but this sin affected the human nature that they would then transmit in a fallen state. It is a sin which will be transmitted by propagation to all mankind, that is, by the transmission of a human nature deprived of original holiness and justice. And that is why original sin is called "sin" only in an analogical sense: it is a sin "contracted" and not "committed" - a state and not an act."
So as the CCC states, though we have not committed the sin, because our human nature has been transmitted to us from Adam and Eve we have contracted the sin. So just as we share in Christ's redemption and life, we also share in Adam's sin and death.
Icons and Statues
To most of us Catholics Icons and statues can be grouped together into a generic “religious art” category. But for the Orthodox, nothing could be further from the truth.
Icons in the Orthodox Church play a very important part in teaching the faith, and their worship. Icons are venerated by the Orthodox not because they are Icons, but because of what the Icon depicts. And just as many Catholic homes have a crucifix, Orthodox homes have an Icon. Once an Icon is blessed and hung in a Church, it can never be removed from that Church. All Icons are hung on an eastern wall facing west due to the symbolism of east representing heaven and the west this world. Icons are full of symbolism and meaning on many, many levels.
Statues on the other hand are a different story. While Icons represent the things of God in an imperfect 2-dimensional way, Statues are rejected by the Orthodox as a form of idolatry due to their 3-dimensional nature.
With the Catholic Church responsible in some way for many of the most beautiful statues in the world, you can see where this may be a point of contention.
So while some of these issues are not big hurdles, others may be. But in the end, the the Churches do share the most important thing of all: the Eucharist. And there is nothing with more unifying power than that.