What is this part of the Mass?
Midway through the Eucharistic Prayer the priest prays that the Holy Spirit will make our gifts we offer, the bread and wine, holy so that they become the Body and Blood of Christ. He then recounts the story of the very first Mass – the Last Supper on Holy Thursday. We call this telling of the Last Supper at Mass, the Institution Narrative. It is the story of Jesus instituting the Eucharist. Every time we come to Mass we remember what Jesus did for us and what he asked us to do. This is a critical part of the Mass and very dear to the heart of Catholics. Pay close attention here – you are about to witness firsthand a great miracle! Usually, you can even hear the people in church become quieter and more attentive as the priest speaks the words of Christ, as he lifts the consecrated host and chalice, and genuflects in adoration to the Real Presence of Christ. Some of the words you will hear at this time will be changing.
 
What do we say now and what is changing?
After the consecration of the bread and wine into the Body and Blood of Christ we move to the Memorial Acclamation. Here we affirm that the risen Christ is with us now and that he will be coming again. We believe because Jesus promised us.

Instead of directing us to give the acclamation “Let us proclaim…”, the priest will simply pronounce, “The Mystery of Faith,” acknowledging the reality that our acclamation is something that wells up from inside us, without prompting. Notice, too, the similarity with two other equally profound pronouncements in the Liturgy: “The Word of the Lord / The Gospel of the Lord,” and “The Body of Christ / The Blood of Christ.”

After the priest makes his pronouncement, we make it clear that we believe in the mystery of faith. This we shall do in one of three ways, all of which sound very familiar and yet changed slightly in the new translation:

The First Option: “We proclaim your death, O Lord, and profess your resurrection until you come again.” When we profess Christ’s resurrection we are saying we believe he rose from the dead and lives today. We believe he will come again in glory at the end of time.

The Second Option: “When we eat this Bread and drink this Cup, we proclaim your Death, O Lord, until you come again.” When we proclaim Christ’s death we profess publicly that we believe he died on the Cross and will come again. The text for the first two options is drawn directly from 1 Corinthians 11:26.

The Third Option: “Save us, Savior of the world, for by your Cross and Resurrection, you have set us free.” In this acclamation, we profess that we believe Christ has freed us from sin by his Dying and Rising. The text for the third option is from John 4:42 and Galatians 5:1.

One significant change in the new Roman Missal is that the familiar acclamation “Christ has died. Christ is risen. Christ will come again” will no longer be used as an acclamation to the Mystery of Faith. The reason for this is that the three options given for the acclamation are all addressed to the Lord. They all note our relationship to Christ’s Paschal Mystery. The acclamation “Christ has died…” does not follow this form and is about the Lord; thus it was not included in the options.

The Eucharistic Prayer ends with the priest praying a prayer of praise to God the Father, through, with, and in Christ; in the unity of the Holy Spirit. This is called a doxology. We respond with (raise hands) “Amen!” The doxology of the priest will be slightly different however. Soon, you will hear these words:
“Though him, and with him, and in him; O God, almighty Father; in the unity of the Holy Spirit; all glory and honor is yours; for ever and ever.”

The main difference here is the word flow, which more closely follows the flow of the Latin. It names the three Persons of the Trinity in succession, so it is easier to tell that the prayer is offered to God the Father, through Jesus Christ, and in the Holy Spirit. Just as we do not sing the doxology with the priest, so he should not sing the Amen with us. The Eucharistic Prayer concludes with a dialogue, just as it began.