The Holy Spirit recalls the mystery of Christ
"By the saving word of God, faith . . . Is nourished in the hearts of believers. By this faith then the congregation of the faithful begins and grows." The proclamation does not stop with a teaching; it elicits the response of faith as consent and commitment, directed at the covenant between God and his people. Once again it is the Holy Spirit who gives the grace of faith, strengthens it and makes it grow in the community. The liturgical assembly is first of all a communion in faith.
Source: Catechism of the Catholic Church (Vatican.va)