I want to summarize the problems with Roman Catholic, which you may be calling Orthodox.
1. Mary Worship, Mariatology
This is a goddess worship, which has been traditional and very much classic throughout the history. Roman Catholic decorated it with Christian label, naming the goddess as Mary, Maria, but its origin was from Ashera, Astarte, Artemis, Aphrodite, Venus, Diana, Shingmu ( in china), etc. which was strictly condemned by God in the Bible.
RC all the time denies that they are worshipping Mary, but they do for Mary more than what they do for the God. If you watch channel 9717 CLAND, catholic channels you can find they are mad in adoring the statue of Mary.
2. Weekly Sacrifice - Mass, which denies the eternal effect of Christ Redemption at the Cross, Once for All.
Ever asking forgiveness, but never bringing the fact and truth that the sins were already forgiven at the Cross.
3. Papacy
This seats the human being where Jesus Christ should sit.
This is groundless title according to the Bible. Many true believers predicted Anti-Christ will come in this title.
4. Purgatory
Most of Catholics confess that they should go to Purgatory first, before they go to Heaven. They are to some extent honest in confessing that they are not qualified for the heaven.
Even the Robber at the Cross went to Paradise directly.
How miserable the Roman Catholics are !
5. Clergy system and Compulsory Celibacy
This is groundless as we know Apostl Peter had his wife, 1 Tim 3 tells us that the Overseer ( Bishop) can be a husband of one wife.
This may be originated from Chemarims ( Zephaniah 1:4)
This contradicts with 1 Pet 2:5-9 which tells us that all the believers are the holy priests.