SOURCE: Abridged and adapted from Ministries and Roles of the Liturgical Assembly at Mass (USCCB)
When the Church comes together in the liturgical assembly to celebrate the Mass, or any other sacrament, her members do not gather simply as a crowd, as an amorphous, undifferentiated group of people. They gather in a variety of ministries and roles.
The first qualification for any participant in the celebration of the Eucharist is that he or she has been baptized into the Body of Christ, the Church. Each time the members of the Church gather to worship, they do so because their baptism demands this of them.
While all share in the priesthood of Christ which delegates them to worship, some members of the Church are called by God to serve in the ministerial priesthood as bishops and priests. Bishops and priests are privileged to act in the liturgy in the very person of Christ, on behalf of his people, pronouncing the most sacred prayers of our faith, presiding over the celebration of the sacred mysteries, explaining God's Word and feeding God's people on the body and blood of Christ.
A bishop has the added responsibility of being the chief shepherd, the principal liturgist of his diocese and in that role is the successor of the Apostles.
Deacons have by God's grace been ordained to a special ministry. In the celebration of the Mass deacons proclaim the Gospel and assist the bishop and priest in exercising their sacred duties.
The celebration of liturgy is not just the responsibility of the pastor, although he is delegated by the Bishop to oversee the liturgical life of the parish. Pastors need the help of their people, the people who are serious about living out their baptismal right and responsibility to worship. Of course, not all members of the parish community will have the time, energy, strength or ability to serve in these roles, however, individuals must be careful not to excuse themselves too easily.
In addition to the ordained ministries there are roles in the liturgy which are exercised by lay people who place their time and talent at the service of the liturgical assembly as acolytes (altar servers), lectors, extraordinary ministers of Holy Communion, cantors, choir members, instrumentalists, leaders of song and ushers. Others contribute their time and talent to planning and organizing the liturgy, to keeping the church and the vestments, vessels and appointments clean and well-ordered or to providing decorations that reflect the spirit of the liturgical feast or season.
All the baptized need to understand that part of their duty regarding liturgy is to accept some responsibility for the liturgy, to place themselves and their God-given talents at the service of the liturgical community whenever possible. If liturgy is a duty as well as a right, then part of that duty for those able to undertake these tasks is the responsibility to assume such key roles in the liturgy.
The General Instruction of the Roman Missal (GIRM) makes it very clear that this variety of offices and roles is desirable and should be maintained. In fact it goes so far as to state: "All, therefore, whether ordained ministers or lay Christian faithful, in fulfilling their function or their duty, should carry out solely but totally that which pertains to them" (no. 91).
Not only, therefore, is it desirable that individuals function in roles of service at Mass, it is clear from the GIRM that if a deacon, for example, is present, the priest celebrant or a concelebrant should not read the Gospel. And the lector should not also take on the role of server and/or extraordinary ministers of Holy Communion. There is a wide variety of services to be performed, and it is desirable that different individuals exercise those services so that the talents and gifts God has placed within the Christian community are fully utilized and these roles of service are not monopolized by a few.
It is not sufficient, however, simply to have a "warm body" filling a given role. Those engaged in liturgical roles need to be well-prepared for those roles and to know how to carry them out with reverence, dignity and understanding. Obtaining the proper preparation requires a further gift of time on the part of the person being prepared as well as on the part of those in the parish responsible for the training of liturgical ministers.
The practical task of assigning individuals to particular Masses and organizing the distribution of roles is another indispensable element in the fabric of well-ordered liturgical ministry in a parish.
But before individuals can be prepared for liturgical roles, there must first be individuals who are willing to assume those roles.
Finally, this catalogue of specialized roles might give the impression that those who are not exercising one of these roles are free to sit back passively and simply let the liturgy happen around them. Nothing could be further from the truth. Those who come together for liturgy do not have the luxury of acting as passive "pew potatoes," waiting for all to be done for them. The liturgy is not only their right, it is their duty, their responsibility, and that responsibility includes full engagement throughout the liturgical celebration.
The liturgy, then, is about the action of God's own people, each with different offices and roles, each office and role, from that of bishop and priest to that of usher and sacristan, one of service, not of privilege, a mirror of Christ who washed the feet of his disciples and instructed his followers to imitate his example of service.