The word Theotokos for “Mother of God” expresses the faith of all the Fathers and faithful Christians throughout the ages concerning Christ’s divinity. There is no room for error here. It was none other than the Second Person of the Holy Trinity who was born of the Virgin. Theotokos: Mother of God.
The identity of Christ is still being questioned today. That is why some bristle when they hear the word Theotokos. How can Mary be the Mother of God? They ask. Was the eternal, always existing God born of a human being? Yes, the Church answers. Mary did not give birth to two persons but to one divine Person who received His humanity from Mary. She is indeed not Christotokos, Mother of a human being named Christ, but Theotokos, Mother of God.
Theotokos is a treasured word for Orthodox Christians – a word that perfectly expresses ad safeguards our faith that the true God became true man for our salvation. Theotokos is a title given to Mary not in order to exalt her but in order to protect the identity of her son and to guard and protect the security of our salvation in Christ Jesus our Lord.
Source: Daily Vitamins for Spiritual Growth Volume 1, by Anthony Coniaris