The Catechism of the Catholic Church defined Faith as follows:
"Faith is the theological virtue by which we believe in God and believe all that he has said and revealed to us, and that Holy Church proposes for our belief, because he is truth itself. By faith "man freely commits his entire self to God." For this reason the believer seeks to know and do God's will. "The righteous shall live by faith." Living faith "work[s] through charity."
Vatican II: Mary become the mother of Jesus by her faith
"By her belief and obedience, not knowing man but overshadowed by the Holy Spirit, as the new Eve she brought forth on earth the very Son of the Father, showing an undefiled faith, not in the word of the ancient serpent, but in that of God's messenger." (2)
(1) CCC 1998 §1814
(2) Vatican II, Lumen Gentium 63