There is only one Sacrament of Holy Orders, but there are three levels:
The first is that which Christ Himself bestowed upon his Apostles: a bishop is a man who is ordained by another bishop. He stands in direct, unbroken line from the Apostles, a condition known as "apostolic succession". Ordination as a bishop confers the grace to sanctify others, as well as the authority to teach the faithful and to bind their consciences. Because of the grave nature of this responsibility, all these ordinations must be approved by the Pope.
The second level of the Sacrament of Holy Orders is the priesthood. No bishop can minister to all of the faithful in his diocese, so priests act, in the works of the Catechism of the Catholic Church, as "co-workers of the bishops." They exercise their power lawfully only in communion with their bishop, and so they promise obedience to their bishop at the time of their ordination. The chief duties of the priesthood are the preaching of the Gospel and the offering of the Eucharist.
The third level of the Sacrament of Holy Orders is the diaconate. Deacons are members of the clergy along with priests and bishops. The deacon’s ministry has three dimensions: liturgy, word and service. At the liturgy, he assists the bishop and priests. At the Mass, the deacon proclaims the Gospel, may be invited to preach the homily, and assists at the altar. The deacon may also baptize, witness and bless marriages, preside at the Liturgy of the Hours, and preside at funeral liturgies among many other duties.
Living in the world, deacons have a particular sensitivity to the needs of real families – including single parents, students, older people, those with disabilities, the incarcerated and those who suffer from poverty or addictions of many kinds.
All Christians are called, but the deacon serves with a special grace – a unique authority and humble power. He is responding to the prompting of the Holy Spirit. He is sent by the Church to be the presence of Christ to those in need.
