The Sacrament of Holy Orders
Holy Orders is the sacrament through which the mission — that is, proclaiming the Word of God and restoring communion with God through prayer and the sacrifice of the Mass — entrusted by Jesus Christ to his apostles is continuously being practiced, and a way by which Christ unceasingly builds up and leads his Church. The outpouring of the Holy Spirit first bestowed upon the Apostles by Jesus on Pentecost, continues to be imparted to generations succeeding them.
Men can be incorporated into the order of bishops, priests and deacons through the sacramental act of ordination, which was instructed by Jesus and honoured in his Church. By this very act and virtue of the sacrament of Holy Orders, the priest embodies Christ himself, and is authorised to act in his power and place.
The Catechism of the Catholic Church explains the roles of Bishops, Priests and Deacons as such:
The bishop receives the fullness of the sacrament of Holy Orders, which integrates him into the episcopal college and makes him the visible head of the particular Church entrusted to him. As successors of the apostles and members of the college, the bishops share in the apostolic responsibility and mission of the whole Church under the authority of the Pope, successor of St. Peter. (CCC #1594)
Priests are united with the bishops in sacerdotal dignity and at the same time depend on them in the exercise of their pastoral functions; they are called to be the bishops’ prudent co-workers. They form around their bishop the presbyterium which bears responsibility with him for the particular Church. They receive from the bishop the charge of a parish community or a determinate ecclesial office. (CCC #1595)
Deacons are ministers ordained for tasks of service of the Church; they do not receive the ministerial priesthood, but ordination confers on them important functions in the ministry of the word, divine worship, pastoral governance, and the service of charity, tasks which they must carry out under the pastoral authority of their bishop. (CCC #1596)
ONLY Bishops can confer the sacrament of the Holy Orders in the three degrees, and it is done so by laying on of hands followed by a solemn prayer of consecration asking God to grant the ordinand the graces of the Holy Spirit required for his ministry. Ordination imprints an indelible sacramental character, which means that their soul has an indelible mark and thus it cannot be removed or taken away from the person.