“Holy Orders is the sacrament through which the mission entrusted by Christ to his apostles continues to be exercised in the Church until the end of time: thus it is the sacrament of apostolic ministry. It includes three degrees: episcopate (bishop), presbyterate (priest), and diaconate (deacon).” (Catechism of the Catholic Church, 1536).
Only baptized, Catholic men are called by the Church to become ordained and receive this sacrament. The man who is ordained a bishop or a priest receives a special grace to act “in persona Christi”, not based on his own power or merit, but in the person of Jesus Christ. Deacons “share in Christ’s mission and grace in a special way” (Catechism of the Catholic Church, 1570) to serve as Christ served.