The answer
The Coptic Church is a member of the Oriental Orthodox family who is made up of six sister churches: Coptic Orthodox, Syrian Orthodox, Armenian Orthodox, Ethiopian Orthodox, Eritrean Orthodox, and Indian Orthodox. The Oriental Orthodox Churches confess the Christological description of St. Cyril of Alexandria, "One Incarnate Nature of God the Logos" as stated in the second item of the declaration. This was the main controversy at the Council of Chalcedon (451 AD) after which the other churches including the Roman Catholic Church separated from our Church. The Oriental Orthodox Churches are also called the 'Non-Chalcedonian' churches by other churches. The Oriental Orthodox Churches have remained steadfast in their orthodox faith and kept the traditions of the Apostles and the teachings of the early fathers, unlike many other Churches that changed some of their dogmas and practices.You can read more about the history of our Church and the writings of our Pope Shenouda III on 'The Nature of Christ' at http://www.copticchurch.net/topics/theology/index.html.
There are a lot of differences between Orthodoxy and Catholicism that hinder us as Orthodox from accepting all the Catholic Church dogmas. The Immaculate Conception, the Purgatory and the Infallibility of the Pope are just a few examples. You can read more about these differences at http://www.geocities.com/mgocsmbvli/orth_cath.htm.
Answered by His Eminence Metropolitan Youssef (opens in a new tab)