Without being too clever about it, one could call the Catholic priesthood the civil service of the Lord. The sacrament is that which guarantees the on-going life of the church - the Body of Christ. Holy Orders maintains that relationship with God that is the right and privilege of His people.
The priesthood is the vehicle that God, through His Son, chose to maintain the regular flow of His grace and blessings through the sacraments. The priest, through this sacrament of Holy Orders, offers sacrifice to God (through the Mass
); forgives sins (through the sacrament of Reconciliation
); heals the sick according to the will of God (through the sacrament of Anointing
); welcomes new people into God's community the church (through Baptism
) and cements with the love of God the union of man and woman in marriage (through the sacrament of Matrimony
The Long View
At our baptism, we become members of the laity (a word derived from the Greek word laos, which means "people"). As people of God, we all share in the priesthood of Christ, and so the Church speaks meaningfully of "the priesthood of all believers." Each of us is to exercise our priesthood by strengthening and serving one another. Within the Church there are many means of service. One way of service stands out as a sacrament, namely Holy Orders, which ordains the recipient to the office of bishop, priest or deacon.
The priest's special calling is first and foremost to preach the Good News of God's love and humanity. In offering himself as a candidate for the priesthood, he must give evidence of wisdom and spiritual maturity, as he is called to lead the Christian community with patience and kindness. The priest says Mass and administers the Sacraments, taking an active role in offering Christ's gift of Himself. During Mass, he represents Christ and also acts on behalf of all the people. Thus his sacramental priesthood stands for the priesthood of the whole Church.
The Church requires that its priests be celibate, although there is nothing incompatible between marriage and the priesthood. Insistence on the matter does not spring from theological difficulties but from Church discipline. A celibate lifestyle, freely chosen, can give witness to Christian values which differ from the fashions of contemporary society. It can provide a unique and valuable freedom to the priest, since it entails a radical departure from expectations, either his own or others', which can be imprisoning. However, there have always been married priests in the Oriental Catholic rites, and married Anglican clergy who have recently become converts to the Catholic Church are allowed to exercise their priesthood.
From earliest times, deacons have had a special place in the pastoral work of the Church, preaching, ministering at baptisms and weddings, and caring for the poor and hungry on behalf of the whole Church. Nowadays, married men are more and more frequently ordained to the diaconate, where they have a strong role in assisting priests and bishops and serving the people.
Finally, bishops are chosen and ordained to supervise and lead priests and deacons, to unify, bless and teach the people and act as a sign of Christ in the local church and community.
Click here for the Catechism of the Catholic Church
Next Sacrament: Matrimony