they both are... both can be traced back to the apostles... even the pope in Rome is given the title "first amounts equal" in the EASTERN ORTHODOX..church.
They with both reunite... together we stand , divided we fall..
pity about the million protestant denomination divided by diff ere interpretation of Scripture (whose canon was decided by the Catholic Church)
Catholic Christians and Orthodox Christians are both apostolic.
All Christians up to the Great Schism of 1054 believed in the papacy. Orthodox are basically (there are a few other minor differences) Catholics that do not believe in the papacy.
Eastern Orthodox. The proof is the fact that we do things the same as 2,000 years ago. There is a famous line- "Orthodoxy- Protestantism without subtractions, Catholicism without additions". Another line " We are Orthodox, but not Jewish. We are Evangelical, but not Protestant. We are Catholic, but not Roman. We are the Eastern Orthodox Church." The Eastern Orthodox Church is the true descendant of the first Christian church. You can go to an Orthodox Church and talk to the priest and he can also explain in detail this to you.
The two churches were one church -- called simply the "Catholic Church", meaning that which was believed everywhere ("Kat' Olin) by Christians -- for over 1,000 years. They both carry the underpinnings of the historical apostolic Christian tradition. The proof is the existence of the Oriental Orthodox (Coptic, Armenian, Syriac, Ethiopian, Eritrean, and Malankara Indian Orthodox0 Church, which separated from the others in the early 400s. Aside from a difference in *how the divine and human natures are expressed in the God-man Jesus Christ, they are essentially the same in these underpinnings as the EO and RC Churches.
No proof is going to satisfy everyone; that's why the two are still separate. These traditions are still held by the Orthodox: the highest authority in the local church is the local bishop, not a far-away super-bishop; the Holy Spirit proceeds from the Father (John 15:26). Each side of these arguments has counter-arguments for the points of the other.
The decision point for me was to see which church had fiddled less with their doctrines since the Great Schism, and which has had fewer schisms off from it later. The Orthodox faith is unchanged, and there have been no lasting schisms of any size.