Many who come to the Sunday Mass are not one of the formal liturgical ministers (presider, greeters/ushers, acolytes, lectors, communion ministers, music ministers, etc.). However, those who are in the pews also exercise the ministry of the assembly, making visible the Church, the Body of Christ. The liturgical assembly makes present the celebration of the paschal mystery. Being part of a liturgical assembly is a privilege of the baptized.
The Constitution on the Sacred Liturgy of the Second Vatican Council teaches us that participation in the liturgy is the right and duty of all the baptized. Indeed, through Baptism, we have been given a share in the priesthood of Christ and are invited to participate in the public worship which is the liturgy of the Church.
The same document also tells us that Christ is present in the liturgy in four unique ways: in the assembled people of God, in the person of the presider, in the Word of God proclaimed, and in the Eucharist broken and shared.