What does a Christian Orthodox believe?

Answer 1

An Orthodox Christian holds the beliefs of the Orthodox Catholic Faith, which was held and taught by the Holy Apostles. It is summarized in the Symbol of Faith, sometimes called the Nicene Creed:

"I believe in one God, the Father Almighty, Maker of heaven and earth, and of all things seen and unseen. And in one Lord Jesus Christ, the Son of God, the Only-Begotten, begotten of the Father before all ages, Light of Light, true God of true God, begotten, not made, of one essence with the Father, by Whom all things were made; Who for us men, and for our salvation, came down from heaven; and was incarnate of the Holy Spirit and the Virgin Mary, and became man. And He was crucified for us under Pontius Pilate, and suffered and was buried. And the third day He rose again, in accordance with the Scriptures, and ascended into heaven, and sits at the right hand of the Father. And He shall come again with glory to judge the living and the dead, Whose kingdom shall have no end. And in the Holy Spirit, the Lord, the Giver of Life, Who proceeds from the Father;

Who with the Father and the Son together is worshipped and glorified; Who spoke by the Prophets; in one Holy, Catholic, and Apostolic Church; I acknowledge one Baptism for the remission of sins; I look for the resurrection of the dead, and the life of the world to come. Amen." The essential beliefs of the Orthodox Christian are therefore very much the essential beliefs of all Christians--the existence of God as Holy Trinity; the Incarnation of the Son as the God-Man Christ Jesus; and His passion, death, and resurrection. Beyond the beliefs stipulated in the Creed, an Orthodox Christian believes in all the doctrines of the Seven Ecumenical Councils, held between AD 325 and AD 787. Orthodox Christians, however, hold that these beliefs are part of an entire way of believing, living, and worshipping that comes to us from the Apostles. This we call "Holy Tradition." Our liturgical worship, our use of the Holy Icons, our prayers for the departed, our veneration of the Saints, and especially of the Mother of God--all of these are part of Holy Tradition. For the Orthodox, it is not possible to accept some parts of this and reject others; these beliefs and practices make up an organic whole, which is nothing more or less than Christianity itself.

Answer 2

They believe in the Triune God: The Father, the Son, and the Holy Spirit.