The first and foremost revealed truth about the Virgin Mary from which all her other roles and all her other honors flow, is her providential role as the Mother of God. This dogma proclaims that the Virgin Mary is true Mother of Jesus Christ, who is God the Son made man. The dogma of Mary’s Divine Motherhood, as it is commonly referred to, was solemnly defined at the third ecumenical council of Ephesus (431 A.D.).
Mary’s role as the Mother of God is revealed in Sacred Scripture. At the Annunciation, the Angel Gabriel declares to Mary: “Behold, you shall conceive in your womb and shall bring forth a son, and you shall call his name Jesus… therefore, the holy one who shall be born of you shall be called Son of God” (Lk 1:31; Lk 1:35).
The angelic message which originates from the Heavenly Father himself attests that Mary becomes the true Mother of Jesus and secondly, that Jesus is the true Son of God. From these words of the angel, we can derive the following simple theological syllogism: Mary is Mother of Jesus; Jesus is God; therefore, Mary is Mother of God. Since Jesus is truly God the Son, and Mary is repeatedly referred to in Scripture as the “Mother of Jesus” (cf. Mt 2:13, 2:20; Jn 2:1, 3; Acts 1:14, etc.), then Mary must be the true Mother of God made man.
St. Paul also witnesses to the Divine Maternity when he states in his letter to the Galatians: “When the fullness of time had come, God sent his Son, born of a woman” (Gal 4:4).
In Tradition, we find the truth of Mary’s Divine Motherhood attested to in the Apostles’ Creed. This ancient and great formula of the essential doctrinal beliefs of the early Church professes faith in “Jesus Christ, his only Son, our Lord, who was conceived by the Holy Spirit, born of the Virgin Mary.”
From the papal and conciliar authority of the Church, we have the historic Marian event of the third ecumenical council, the Council of Ephesus in 431 A.D. Ecumenical councils are those general assemblies of bishops who, with the authority and confirmation of the pope and guided by the Holy Spirit, teach and define doctrine as found in divine revelation, which are subsequently binding on the universal Church (hence, the name ecumenical or general council).
The Council of Ephesus solemnly declared the Blessed Virgin Mary to be the Mother of God or “Theotokos”—literally the “God-bearer.” The Council approved the teaching of St. Cyril of Alexandria who, against the errors of Nestorius, Patriarch of Constantinople, declared:
If anyone does not confess that the Emmanuel (Christ) in truth is God and that on this account the Holy Virgin is the Mother of God (Theotokos) in as much as she gave birth to the Word of God made flesh…let him be anathema. (1)
Nestorius refused to call Mary “Mother of God” not primarily because of a Mariological error, but because of a Christological error concerning the nature and personhood of Jesus Christ.
Nestorius erroneously referred to the Lord Jesus as being of two separate persons, one divine and one human, instead of the true and necessary doctrine which was to become known as the “Hypostatic Union“: that Jesus Christ is one divine person, with both a divine and a human nature. (2) When Nestorius refused to call Mary the “Theotokos” or God-bearer, but only the “Christotokos” or mother of the human nature of Christ, it revealed his Christological error which denied the profound Hypostatic Union of both the divine and human nature in the one divine person of the Lord. The Ephesus definition about the Blessed Virgin actually protects the doctrinal orthodoxy regarding Jesus Christ.