Maybe these comments, from a Catholic apologist, will help:
“I would say that most Orthodox see themselves as the true church in as much as all Apostolic churches are authentic and therefore hold authority to teach, preach and admonish. Each Patriarch is almost like a mini pope, holding virtually total authority over his respective church. He is not isolated however, the universal church shares a role in forming doctrine, namely the creeds; but jurisdictional matters are seldom handled beyond the individual Patriarch.
I have not met an Orthodox who does not hold the Catholic Church to be apostolic and therefore authentic. They do consider us flawed on several issues, but valid just the same.
It is our apostolicity that can become a fertile ground for discussion.
It is most important to bring into a discussion with regards to Peter’s unique authority. They may counter you and point to Mt 18, where Jesus gives all the Apostles the power to bind and loose, but drawing the distinction between the two events is critical. In Mt 16, Peter alone is given the keys, a symbol drawn directly from Isaiah 22, where Shebna was removed as Master of the Palace and the keys were given to Elikiah, and to his descendants for all posterity. Compare the language of the two instances and you will see how Jesus modeled his own handing on of the keys after this very incident.
Understanding the context of Isaiah is important to dicipher Mt 16. Shebna was virtually the Prime Minister of King David’s cabinet. He had the authority of the king to act in his name, and was uncontestable. Only the king himself could override him. In Jesus kingdom, Peter becomes the new master of the Palace, or prime minister, acting in place of the king (Jesus) in all matters regarding authority. While Jesus did give all the apostles his authority to bind and loose, only Peter is given the distinctive symbol of the keys, that symbol which represents Christ’s own authority, trumping all others. His primacy is therefore not only “a first place” among the apostles, but of a unique character that is set above. It is not merely a token privilege but a practical one, enabling Peter to settle disputes among the bretheren should problems arise, or to settle matters regarding doctrine and practice. Keys = authority, it’s that simple. The Orthodox know very well that Apostolicity means handing down authority, not something that dies with the person. Peter’s office continues, just as Elikiah’s did, to all the “little jugs, bowls and dishes.”
the Catholic Church claims to hold the seat of Peter, the Papacy, and therefore the charism of primacy and supremacy. Our debate with the Orthodox is chiefly over this point; they concede primacy, but not supremacy, to Peter’s seat.
We hold that the Papacy is the critical seat of unity for the Church that Christ built (he only built one) and therefore the Orthodox are the scismatics. The day we work out this issue we will likely restore the unity that Christ desired for His Church. Our present Pope has made it a priority for his papacy, to unify the “lungs” of the Body of Christ.”
Also, see this timeline for a better historic background:
raeshomepage.bravehost.com/orthodox.html
raeshomepage.bravehost.com/orthodox2.html
Also see:
Why I’m not Eastern Orthodox (by Jimmy Akin)
catholic.com/thisrock/2005/0504bt.asp
A Response to Orthodox Critiques of Catholic Apostolicity
socrates58.blogspot.com/2007/03/response-to-orthodox-critiques-of.html
and
raeshomepage.bravehost.com/meaning.html
What Does Catholic Mean?