Each time we come together as the Body of Christ to celebrate the Eucharist, we are doing what we were baptized to do! Our baptism gives us a share in the priesthood of Christ, and this allows us to be one with Christ in his self-offering to God. The liturgy of this offering, the Mass, is not initiated by us but by God. The liturgy is in fact a gift from God, who acts in and through the Church, the Body of the risen Christ. It is our action only to the extent that we give ourselves to this mystery of redemptive worship. When we gather for the Eucharistic liturgy, the center of the whole Christian life (General Instruction, #16), we do so because our baptism calls us to it and empowers us for it. Different Roles, Indispensable Ministries
It is the whole community, the Body of Christ united with its Head, that celebrates the liturgy (see Catechism of the Catholic Church, #1140). As the Body of Christ, the Church, we each and all have a very important and necessary role in the celebration of Mass. Saint Peter reminds us that we are “a chosen race, a royal priesthood, a holy nation, a redeemed people” (1 Peter 2:9–10). In the celebration of the Eucharist, the Church is her truest self. Because God has redeemed the Church in Christ we are able to come before God and offer our praise and thanksgiving in the Church’s liturgy.
All the baptized, the whole community, the holy People of God, are united with Christ, but some members of the Church are called to special service of Christ in the community of the Church. They are called to service in duties of their own. Tasks not specifically reserved to the ordained ministers should be fulfilled by the lay faithful and exercised by them in conformity with their specific lay vocation.