Let us explore the biblical references for addressing Mother Mary as the Mother of God.

When Elizabeth heard Mary’s greeting, the child in Elizabeth’s womb leaped for joy and Elizabeth filled with the Holy Spirit proclaimed “Most blessed are you among women, and blessed is the fruit of your womb. And how does this happen to me, that the mother of my Lord should come to me?” (Luke 1: 42-43). Elizabeth filled with the Holy Spirit addresses Mary as the “Mother of my Lord”. Luke uses the Greek word ‘Kyrie’  for ‘Lord’ within the same chapter multiple times which clearly references ‘God’. The same word ‘Kyrie’ is used in the following verses ‘Observing all the commandments and ordinances of the Lord’ (Luke 1:6); ‘sanctuary of the Lord ‘(Luke 1:9); ‘the angel of the Lord’ (Luke 1:11)

The Catholic Church proclaims that Mary is truly the Mother of God since the One whom she conceived as man by the power of the Holy Spirit(Luke 1:35) is the second person of the Holy Trinity, is the son of God (Luke 1:35), is word made flesh (John 1:1), is our Lord Jesus Christ. (CCC 495)

Theotokos is a Greek word which stands for “God-Bearer”. Jesus Christ is fully God and fully human at the same time. This means that from the moment Mother Mary conceived Jesus by the power of the Holy Spirit, the child in her womb was already God. Thus she attains the status of God bearer and hence she is rightly addressed as the Mother of God.