Can someone explain in a concise way the difference between RC and Eastern Orthodox? Why do they say they are the true church and RC is not?
I’ll try to be as concise as possible, especially since I am a convert from Catholicism.
1.) The biggest difference is over the papacy and Papal Supremacy. The Orthodox do not believe that the bishopric of Rome holds any more theological significance than any other bishopric. They recognize its historical significance, but feel that today it has fallen into heresy/heterodoxy. And while they recognize its Petrine status, they do not see how its Petrine status differs from either Antioch or Alexandria’s. In the past, they only recognized Rome as First Amongst Equals in honor.
2.) Original Sin (Catholic/Protestant) vs. Ancestral Sin (Orthodox). Today, the Catholic Church and the Orthodox Church do not differ significantly from their understanding of Man’s fallen nature. However, in the past the Latin West often bought wholesale into Augustine’s extreme positions on Original Sin and even endorsed predestination. So while this difference is no longer existent, it is still something to be aware of.
3.) Communion. Catholics generally wait until a child reaches a certain age before allowing them to receive communion. Orthodox, however, allow them to receive it regardless of age.
4.) Confession. Unlike Catholicism, Orthodox usually have to schedule a personal meeting with their priest for confession. There is no weekend period for confessions as with most Catholic parishes in the USA. Additionally, the confession generally takes much longer, as long as 2-3 hours in some cases, because the priest wants to know all of the details and circumstances of your problems. The priest gives a penance, but the purpose is less tied up with the idea of Purgatory (which the Orthodox reject), and is more concerned with helping you avoid the situations that give rise to sin or at least helping you overcome them. The advice is usually more than a prayer and is specific.
5.) Marriage. Orthodox regard marriage as a sacrament. However, they also recognize that is not the same as baptism, which is forever (since Christ himself granted ground for divorce). So should a marriage tragically fail, they may grant a canonical divorce (not to be confused with an annulment) and allow for a second marriage. But the ceremony for a second marriage involving a divorce is kept solemn in acknowledgment of the participant’s past failure.
6.) Birth Control. Orthodox all condemn abortifacients. That being said, the position on other methods of birth control is not unanimous, such as with condoms. Many have no problem with it as long as it is used within a marriage and in consultation with the parish priest. Others hold a position much closer to the Roman Catholic position, but also generally reject Natural Family Planning too.
7.) Filioque. Orthodox reject the filioque clause of the creed for at least the reason that it inserted into the Nicene Creed unilaterally. Most also believe it to be heretical. The topic is a deep one, so I cannot give an adequate summary about the matter here. As for my own interest in Orthodoxy, I didn’t really pay much attention to the Filioque until after I converted.
Seven general differences seems to be a good number to stop at. I also recommend attending an Orthodox service in English if possible so you can experience more of its flavor. As for why we consider ourselves the one true church, that’s a matter that is of more historical concern. I feel like I’ve already explained a little bit of this aspect of it. That being said, I would be more than happy to provide you with a list of academic books and articles written by Catholics, Anglicans, Orthodox, and secularists on the matter. That way you can reach your own conclusions without fear of severe bias, whatever course of conversion you wind up taking (or staying where you are). Just let me know if you’d like me to share with you my list of suggested reading materials concerning this historical issue.
Note for my Catholic friends: I realize some of these claims, particularly the historical ones, will undoubtedly cause you to object. However, please recognize that I am merely presenting the general Orthodox perspective on the question that the OP asked. I am not asking for a debate, nor will I engage in one on this thread.
