Author John Baggley writing about the Annunciation says:
“Just as for St. Luke the event has profound theological implications, so for the Church there is a continuous exploring and relishing of the implications of our humanity being taken by God the Son in the womb of the Virgin Mary, to be redeemed, perfected, and raised to glory. The Virgin’s ‘Yes’ to God reverses the sin of Eve, and begins to reverse the consequences of the fall. Time and again we are reminded that whereas the serpent’s deception beguiled Eve, kindled human pride and led to the fall, the Archangel’s message of the redeeming love and humility of God leads to the Virgin’s obedience and the accomplishment of God’s work of redemption through the Incarnation. The fruit of Eve’s deception is the curse, especially in relation to the pain of childbearing, whereas the fruit of Mary’s obedience is joy, with the conception of the Child who is both God and man. The Archangel’s greeting is often rendered as ‘Rejoice!’ in the hymnody of the Feast, for it is more than a simple greeting; Mary is to rejoice because of her vocation, and what is to be accomplished through her; and joy will be the hallmark of the renewed humanity that is brought to life through the self-giving and humility of God’s human birth. ‘Now God becomes man, that he may make Adam God.’ What greater statement of the doctrine of theosis – the taking up of human life into union with God – could there be?
Today there come glad tidings of joy: it is the feast of the Virgin. Things below are joined to things above. Adam is renewed, and Eve set free from her ancient sorrow; and the Tabernacle of the human nature which the Lord took upon Himself, making divine the substance He assumed, is consecrated as a Temple of God. O mystery! The manner of his emptying is unknown, the fashion of his conceiving is ineffable. An angel ministers at the wonder; a virgin womb receives the Son. The Holy Spirit is sent down; the Father on high gives his consent; and so the covenant is brought to pass by common counsel. In Him and through Him are we saved, and together with Gabriel let us cry aloud unto the Virgin: ‘Hail, thou who art full of grace: the Lord is with thee. From thee has Christ our God and our Salvation taken human nature, raising it up unto Himself. Pray to Him that our souls may be saved.’
In Jerusalem by the fifth century the celebration of the Annunciation was regarded as the occasion when the Fathers of the Church who had upheld the doctrine of the Incarnation should be honored. In Constantinople during the sixth century, because of the growing significance of the commemoration of the Mother of God, the celebration of the Annunciation was taken out of the immediate Christmas period and given a feast in its own right: 25th March, nine months before Christmas, became the date for celebrating the Annunciation.”
(John Baggley, Festival Icons for the Christian Year, pp 23-24)