The following observations are from a follower of Christ who is neither Catholic or Protestant: Martin Luther was a Catholic priest before he was defrocked. He tried to “reform” from within.
That Mary, mother of Jesus, the Christ, is the Mother of God is a dogma not found in scripture. This doctrine does go back to names like Nimrod and Astoreth.
Actually it is implied in Scripture.
If you read the Gospel of Luke, when Mary visited her cousin Elizabeth, she said, “How is it that the Mother of my Lord, should come to me.”
In Hebrew tradition. God’s name is never invoked instead, when the Jews address God, they often use the term, Lord, or Adonai in Hebrew. So the when Elizabeth addressed Mary, Mother of my Lord, it come be written as “Mother of my God.”
The doctrine is deep in Scripture is it is also founded in Early Church History.
The fourth and fifth centuries, the first ones of Christian emancipation from persecution, were centuries of consolidating the truth about God and Christ. The Councils of Nicea (325) and Constantinople (361) defined the basic teachings of Christianity in the Creed which goes by their name (and which is obligatory at Sunday Mass), against those who in one manner or another denied the unity of God, and the Divinity of the Son (“one in substance with the Father”) and of the Holy Spirit (“who proceeds from the Father and the Son”). It also asserted the true humanity of Christ “born of the Virgin Mary,” thus protecting the Incarnation of the Word, the Word-made-flesh, from the assault of heretics like Arius. Jesus Christ was indeed the Eternal Son, a Divine Person, who united in Himself both a Divine and human nature.
However, some of those who remained in the Church after Nicea-Constantinople sought to mitigate the full force of these teachings by various equivocations. In 428 Archbishop Nestorius, the newly elected Patriarch of Constantinople, began to teach that Mary was indeed the Mother of Christ but was not the Mother of God, a title freely used in the Church. Although attempting to remain faithful to the Creed, that is professing belief in Christ’s true Divinity and true humanity, Nestorius’ writings, however, suggested that in Christ there was more of a moral unity of two persons, the Word and Jesus. In addition to the rebellion of the clergy and people, Nestorius had to contend with the attacks of St. Cyril of Alexandria, who finally submitted both Nestorius’ writings and his own defenses to Pope St. Celestine, who condemned Nestorius as a heretic.
Nestorius was only emboldened, teaching that Jesus was merely the temple of the Word, and if Mary is the Mother of God she has been made a goddess. His contemptuous remarks included, “a mother cannot bear a son older than herself.” Both the Pope and Nestorius were desirous of a Council and so one was called in Ephesus in June of 431. However, Nestorius and his followers did not come, despite several summons, and after seven sessions to consider the matter the teaching of Nestorius, and some other heretics such as Pelagius, were condemned. Here is what the Council decreed:
111a For we do not say that the nature of the Word was changed and made flesh, nor yet that it was changed into the whole man (composed) of soul and body but rather (we say) that the Word, in an ineffable and inconceivable manner, having hypostatically united to Himself flesh animated by a rational soul, became Man and was called the Son of Man, not according to the will alone or by the assumption of a person alone, and that the different natures were brought together in a real union, but that out of both in one Christ and Son, not because the distinction of natures was destroyed by the union, but rather because the divine nature and the human nature formed one Lord and Christ and Son for us, through a marvelous and mystical concurrence in unity. . . . For it was no ordinary man who was first born of the Holy Virgin and upon whom the Word afterwards descended; but being united from the womb itself He is said to have undergone flesh birth, claiming as His own the birth of His own flesh. Thus [the holy Fathers] did not hesitate to speak of the holy Virgin as the Theotokos (Mother of God). [Denzinger paragraph 111a]
113 Canon. 1. If anyone does not confess that God is truly Emmanuel, and that on this account the Holy Virgin is the Mother of God (for according to the flesh she gave birth to the Word of God become flesh by birth), let him be anathema (condemned, i.e. excommunicated).
114 Can. 2. If anyone does not confess that the Word of God the Father was united to a body by hypostasis [union in a single Person] and that one is Christ with his own body, the same one evidently both God and man, let him be anathema.
115 Can. 3. If anyone in the one Christ divides the subsistences [divine and human natures] after the union, connecting them by a junction only according to worth, that is to say absolute sway or power, and not rather by a joining according to physical union [union in the one Christ], let him be anathema.
116 Can. 4. If anyone portions out to two persons, that is to say subsistences, the words in the Gospels and the apostolic writings, whether said about Christ by the saints, or by Him concerning Himself, and attributes some as it to a man specially understood beside the Word of God, others as befitting God alone, to the Word of God the Father, let him be anathema.