Today we celebrate the Solemnity of Mary the Holy Mother of God or “Theotokos.” From antiquity, Mary has been called "Theotokos" (Greek), or "God-Bearer" (Mother of God) and the term was used as part of the popular piety of the early first millennium church. It is used throughout the Eastern Church's Liturgy, both Orthodox and Catholic. It lies at the heart of the Latin Rite's deep Marian piety and devotion. This title was a response to early threats to “orthodoxy, the preservation of authentic Christian teaching: a pronouncement of an early Church Council, The Council of Ephesus in 431 A.D., insisted ‘If anyone does not confess that God is truly Emmanuel, and that on this account the holy virgin is the "Theotokos"’ (for according to the flesh she gave birth to the word of God become flesh by birth) let him be anathema." (The Council of Ephesus, 431 AD).

The Council's insistence on the use of the title reflected an effort to preserve the teaching of the Church that Jesus was both Divine and human, that the two natures were united in His One Person. Not only was that teaching under an assault then, it is under an assault now, and failing to "get it right" has extraordinary implications. The reason that the early Church Council pronounced this doctrine was "Christological,” meaning that it had to do with Jesus Christ. One of the threats was from an  interpretation of the teachings of a Bishop of Constantinople named Nestorius. Some of his followers insisted on calling Mary only the "Mother of 'the Christ". The Council insisted on the use of the title (in the Greek) "Theotokos," ("Mother of God" or "God-bearer") to reaffirm the central truth of what occurred in the Incarnation of Jesus Christ.

Rejection of the truth revealed in this beautiful title of Mary has led to a diminution in the understanding and role of Mary, impeding some Christians from grasping a deeper truth concerning the meaning of Mary's life - her Fiat, her "Yes" to God's Will. It is a privation, leading to a reduced
understanding of the call to every Christian to live our lives for God as Mary did. It has undermined our mission to bring the world to the new world, recreated in her Son, the Church which is His Body on earth and a seed of the Kingdom which is to come. The Church, of which we are members through baptism, continues His redemptive mission until he returns.

When we fail to receive the gift of Mary as Mother we can also miss the call of every Christian to bear Jesus for the world as she did. It is time to re-examine the deeper implications of the treasure that is found in the life example and message of the little Virgin of Nazareth. This wonderful title, Mary, the Mother of God, "Theotokos," reveals a profound truth not only about Mary, but about each one of us. We are now invited into the very relationship that she had with her Son. We can become "God-bearers" and bring Him to all those whom we encounter in our few short days under the sun. (Taken from article written by Deacon Keith Fournier; Catholic Online, 2016)