The church commemorates the assumption of St. Mary's body into heaven through St. Mary's fast, celebrated every year August 7-21. The early Church Fathers had no problem referring to St. Mary as the Mother of God. They saw it as a natural consequence of the Incarnation.
1) St Irenaeus said, "The virgin Mary, being obedient to His word, received from an angel the glad tidings that she would bear God." (Against Heresies 5:19:1 [A.D. 189])
2) St. Peter of Alexandria said, "They came to the church of the most blessed Mother of God, and ever-virgin Mary, which, as we began to say, he had constructed in the western quarter, in a suburb, for a cemetery of martyrs." (The Genuine Acts of Peter of Alexandria [A.D. 305])
3) St. Cyril of Alexandria said, "I have been amazed that some are utterly in doubt as to whether or not the holy virgin is able to be called the Mother of God. For if our Lord Christ is God, how should the holy virgin who bore him not be the Mother of God?" (Letter to the Monks of Egypt [A.D. 427])
By: Fr. Mikhail E. Mikhail, D. Min.