St. Cyril of Alexandria, The Twelve Anathemas 1 & 2 (430 AD)
If anyone does not confess that the Emmanuel is in truth God, and that the
Holy Virgin is Mother of God, because she bore according to the flesh of
the Word of God when He became flesh: let him be anathema;
If anyone does not confess that the Word of God the Father is united
hypostatically to the flesh, and that Christ with His own flesh is one, that is
to say, the same one is God and Man at the same time: let him be
anathema.
St. Cyril of Alexandria, Scholia on the Incarnation of the Only-
Begotten 26 (post 431 AD)
The Word, then, was God, and He became also Man; and since He was
born according to the flesh for the sake of mankind, it is necessary that she
who bore Him is the Mother of God. For if she did not bear God, neither is
He that was born of her to be called God. If the divinely inspired Scriptures
name Him God, as God having been made man and incarnate, He could not
become Man in any other way than through birth from a woman: how then
should she who bore Him not be the Mother of God?
Catechism of the Council of Trent (1566)
Pt. I, Ch. IV: Glory to God in the highest; and on earth peace to men
of good will. Then began the fulfillment of the splendid promise made by
God to Abraham, that in his seed all the nations of the earth should one day
be blessed; for Mary, whom we truly proclaim and venerate as Mother of
God, because she brought forth Him who is at once God and man, was
descended from King David.
Catechism of the Catholic Church (1992)
No. 495:
Called in the Gospels the mother of Jesus, Mary is
acclaimed by Elizabeth, at the prompting of the Spirit and even before the
birth of her Son, as the mother of my Lord. In fact, the One whom she
conceived as man by the Holy Spirit, who truly became her Son according