179. Why did Christ institute an ecclesiastical hierarchy?

Christ instituted an ecclesiastical hierarchy with the mission of feeding the people of God in his name and for his purpose gave it authority. The hierarchy is formed of sacred ministers,; bishops, priests, and deacons. Thanks to the sacrament of Orders, bishops and priests act in the exercise of their ministry in the name and person of Christ the Head. Deacons minister to the people of God in the diakonia (service) of word, liturgy, and charity.

Further reading: CCC 874-876, 935

180. How is the collegial dimension of Church ministry carried out?

After the example of the twelve Apostles who were chosen and sent out together by Christ, the unity of the Church's hierarchy is at the service of the communion of all the faithful. Every bishop exercises his ministry as a member of the episcopal college in communion with the Pope and shares with him in the care of the universal Church. Priests exercise their ministry in the presbyterate of the local Church in communion with their own bishop and under his direction.

Further reading: CCC 876-877

181. Why does ecclesial ministry also have a person character?

Ecclesial ministry also have a personal character in as much as each minister, in virtue of the sacrament of Holy Orders, is responsible before Christ who called him personally and conferred on him his mission.

Further reading: CCC 878-879