Through the Sacrament of Holy Orders, a baptized man is configured to Christ by a special grace of the Holy Spirit through the laying on of hands, becoming another Christ (alter Christus) so that he can stand in the very Person of Christ (in persona Christi) among those he serves. The grace of ordination imparts a permanent seal or mark on his soul that conforms him to Christ in a deep and particular way.
There are three degrees of Holy Orders in the Catholic Church: Bishop, Priest, and Deacon. Each of these degrees are described below.
Bishops receive the fullness of Holy Orders and can trace their ordination in succession all the way back to the Apostles themselves. The importance of this apostolic succession for the preservation of the Church’s teaching is clearly documented as early as the second century, and indeed in Scripture itself. Bishops receive the office of Jesus for sanctifying, teaching, and guiding or governing the faithful under their care. They are assigned by the Pope to serve the Church in a particular geographic area called a Diocese or Archdiocese, and they share in the Pope’s responsibility for the whole Church as his brothers.
Priests are also ordained into Jesus’ ministerial priesthood, but to a lesser degree. They serve as co-workers with their bishops, to whom they promise obedience and by whom they are ordained, and he assigns them to serve the people in a particular parish or ministry and to share in his office of sanctifying, teaching, and governing. As priests, they receive from Christ the power to forgive sin and to offer the Mass.
Deacons are also ordained by the bishop, but not to the priesthood. A deacon’s ministry is one of service, so that bishops and priests may focus primarily on those duties reserved to them. Deacons may assist at the Mass, preach and teach, witness and bless marriages, preside at funerals, baptize, and carry out works of charity, but they cannot hear confessions or offer the Mass.
Holy Orders is a call from God, not to be confused with a career choice or a right that anyone can invoke. Like Matrimony, it is a Sacrament of Service or Vocation. Unlike the Sacraments of Initiation (Baptism, Confirmation, Eucharist), which are intended for everyone in the Church, Holy Orders is a call given only to some and only to men. It is a gift given as God wills and the Church confirms, not because of what a man can do but because of what he has become through ordination.