From the Catechism of the Catholic Church
“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 to the flesh, was none other than the Father’s eternal Son, the second person of the Holy Trinity. Hence the Church confesses that Mary is truly “Mother of God” (Theotokos),” (CCC 495).
“Mary is truly “Mother of God” since she is the mother of the eternal Son of God made man, who is God himself,” (CCC 509).
“Mary, the all-holy ever-virgin Mother of God, is the masterwork of the mission of the Son and the Spirit in the fullness of time. For the first time in the plan of salvation and because his Spirit had prepared her, the Father found the dwelling place where his Son and his Spirit could dwell among men. In this sense the Church’s Tradition has often read the most beautiful texts on wisdom in relation to Mary. Mary is acclaimed and represented in the liturgy as the “Seat of Wisdom.” In her, the “wonders of God” that the Spirit was to fulfill in Christ and the Church began to be manifested,” (CCC 721).