14 Mary's faith can also be compared to that of Abraham, whom St. Paul calls "our father in faith" (cf. Rom. 4:12). In the salvific economy of God's revelation, Abraham's faith constitutes the beginning of the Old Covenant; Mary's faith at the Annunciation inaugurates the New Covenant. Just as Abraham "in hope believed against hope, that he should become the father of many nations" (cf. Rom. 4:18), so Mary, at the Annunciation, having professed her virginity ("How shall this be, since I have no husband?") believed that through the power of the Most High, by the power of the Holy Spirit, she would become the Mother of God's Son in accordance with the angel's revelation: "The child to be born will be called holy, the Son of God" (Lk. 1:35). However, Elizabeth's words "And blessed is she who believed" do not apply only to that particular moment of the Annunciation. Certainly the Annunciation is the culminating moment of Mary's faith in her awaiting of Christ, but it is also the point of departure from which her whole "journey towards God" begins, her whole pilgrimage of faith. And on this road, in an eminent and truly heroic manner- indeed with an ever greater heroism of faith-the "obedience" which she professes to the word of divine revelation will be fulfilled. Mary's "obedience of faith" during the whole of her pilgrimage will show surprising similarities to the faith of Abraham. Just like the Patriarch of the People of God, so too Mary, during the pilgrimage of her filial and maternal fiat, "in hope believed against hope." Especially during certain stages of this journey the blessing granted to her "who believed" will be revealed with particular vividness. To believe means "to abandon oneself" to the truth of the word of the living God, knowing and humbly recognizing "how unsearchable are his judgments and how inscrutable his ways" (Rom. 11:33). Mary, who by the eternal will of the Most High stands, one may say, at the very center of those "inscrutable ways" and "unsearchable judgments" of God, conforms herself to them in the dim light of faith, accepting fully and with a ready heart everything that is decreed in the divine plan.
Source: Redemptoris Mater (Vatican.va)