The Orthodox Church beliefs are captured in the Nicene Creed, adopted by the First Ecumenical Council of Nicaea, in 325. It is recited in each liturgy and is as follows:
I believe in one God, Father Almighty, maker of heaven and earth, of all things visible and invisible.
And in one Lord Jesus Christ, the Only Begotten Son of God, begotten of the Father before all ages. Light of Light, true God of true God, begotten, not created, of one essence with the Father; through whom all things were made.
Who for us men and our salvation, came down from heaven, and was incarnate by the Holy Spirit and the Virgin Mary, and became man.