How does the Orthodox Church view the Roman Catholic Church?
Specifically
Yes and no. The Catholic Church was initially considered by the Orthodox Church to be heretical, but as time passed and the term began to have strong negative connotations, the term was changed to heterodox, at least in official discourses. However, hardliners are still using the term heretic. In what matters? Well, the first one would be the filioque controversy. Search for it on this site, it's discussed in numerous threads. Other issues like the Easter date, celibacy of priests, unleavened bread used for the eucharist, withholding the Holy Blood (eucharistical wine) from the laity, using the organ in church music, papal primacy, papal infallibility etc. are considered by the Orthodox Church to have no basis in the Holy Scripture or the Holy Tradition (teachings of the Church Fathers) and thus they are not orthodox, but heterodox.
I come from a catholic family so I was baptized catholic. I converted to orthodox christianity a few years ago, and the conversion did not include a baptism. This is because the catholic baptism is considered valid by the Orthodox Church. Both Churches have apostolic succession (by laying on of hands) so both orthodox and catholic priests received the Gifts of the Holy Spirit on ordination. Baptisms performed by other denominations are not considered valid (especially the ones from the non-trinitarian denominations, because a person has to be baptized in the name of The Father, The Son and The Holy Spirit). Eucharisty on the other hand is not considered valid. Furthermore, it is strictly prohibited to give the Holy Communion to non-orthodox people. I'm not 100% sure, but this should be the same in the Catholic Church also.
Attending Mass in other churches is not prohibited. In both Orthodox and Catholic Christianity the reason one calls a priest father is because he is one's spiritual parent, guiding him in his spiritual endeavours. Penance should not be just an enumeration of your sins, but also a desire to not repeat them and asking the priest for guidance, which he provides based on the teachings of the Church. It would be a kind of nonsense to be orthodox and seek guidance from a catholic priest (offering advice based on catholic teachings) or viceversa. If one feels like doing so, for whatever reason, then why not convert?
I'm romanian, and most of the information in this answer I learned from the writings of romanian orthodox monks, priests and theologians (also some greek, russian and Church Fathers writings).
I confess that I have had difficulty finding Eastern Orthodox books that indicate their position, historical or otherwise on other Christian groups. I have found one fairly good source written by a Catholic (Adrian Fortescue) that makes at least eastern Orthodox historical thought pretty well.
Adrian writes:
It was natural that, soon after the Reformation, the Protestants, who had thrown off the Pope's authority, should remember and try to set up relations with the people in the East of Europe who, as far as this point went, had already for centuries stood in the same position. It is to the credit of the conservative spirit of the Orthodox Church that she has always refused communion with any religious body except on terms of the complete acceptance of the Orthodox faith. As we shall see, she believes herself to be the whole and only real Church of Christ, just as Catholics do. So any sort of alliance with other Churches on mutual terms is impossible, and the idea, often cherished, of building up a great united anti-papal Church to rival and balance the Catholic body has always broken down because of her refusal, as well as for other reasons. The Orthodox EasTern Church, Adrian Fortescue (p252)
Then he goes on to explain various attempts of Protestants to try and build ties with the Eastern Orthodox Church and why it was impossible, listing among other things that the Protestants had a unacceptable view of Justification by Faith. He also lists that the Eastern Church rejects papal authority, purgatory, immaculate conception, and the phrase "the Spirit proceeds from the Son" (Filioque) as reasons why the Eastern Church considers the Roman Catholic as heretical.
From another source (this time written by an author within the Eastern Orthodox Church) we have a similar description:
Hence this church only cuts off all those who either do not receive the word of God, or mix their own improper opinions with it; therefore, the society of such people is not a church, but an assembly holding heterodox opinions, which is governed by the spirit of division, and not by the Spirit of God. Even at the present time, to the offence of Christians, we behold three chief sects or parties in Christianity; Papists, Lutherans, and Calvinists. They are mutually in opposition to one another. Popery, exclusive of its being filled with the most pernicious superstitions, and the edicts of Popes, in contradiction to the word of God, blindly holds the tenet in regard to the proceeding of the Holy Ghost above-mentioned, and explains it in opposition to the clear testimony of Holy Scripture. (A Summary of Christian Divinity by Platon, p162)
Therefore, it seems, at least from any actual published works (as old as these references are) within and without the Eastern Orthodox Church that "she believes herself to be the whole and only real Church of Christ, just as Catholics do".
Note: There will always be some ecumenical movements are claims by every church but without official recognition by top leaders these movements are always a little confusing and often greatly opposed by their leaders. To prove any real ecumenical stances one has to quote something officially recognized as canonical which seems impossible to find. However quoting from leaders in terms of rejection the other churches seems less difficult. Therefore as old as the quotes I have been able to find are, I actually trust them more then any random opinion found on the internet.
To be clear:
1. Does she consider RCC herectical? In what matters? - The Orthodox Church considers the RCs to have left the historic Church (i.e. the Orthodox Church), having introduced the idea that one man (i.e. the Pope of Rome) has authority over all Church Councils. Later doctrines - such as the filioque in the Creed, the created fire of purgatory, and Scholastic rationalism throughout RC theology - have added to this estrangement of the RCs from historic Christianity.
2. Does she consider RCC priesthood and sacraments as valid? No. Anyone who suggests that this is the view of the Orthodox Church is playing fast and loose with the historical understanding of the Orthodox Church: when Rome left Her, Rome left behind that which Christ gave to His Church. While most Orthodox would acknowledge Christian elements that are preserved in Roman Catholicism, it would still be seen as fully estranged from the historic Church.
3. Does she allow her children to attend RC Mass and receive the Eucharist or the Sacrament of Penance? No. Orthodox Christians who received RC communion or other rites would place themselves out of Communion with the Orthodox Church, and would have to go through certain pastoral and canonical steps to be reconciled. While an orthodox Christian might attend an RC wedding or funeral as a non-participant, anything more than this would be problematic (at minimum).
My Eastern Orthodox Christian priest told me Catholics have valid Eucharist and priesthood. Also, the archpriest in the Eastern Orthodox Church that baptized me said it’s ok to become Catholic if I want to because it’s the faith that is important and I think he said they share the same faith.
So I think you’ll find different beliefs about Catholics among Orthodox whereas Catholics basically believe what their catechism teaches.
