The Catechism of the Catholic Church explains the Sacrament of Holy Orders.  Its teaching is found starting with paragraph 1536.  There are two participations in the one priesthood of Christ: baptismal priesthood and ministerial priesthood.  The faithful exercise the baptismal priesthood and deacons, priests and bishops exercise the ministerial priesthood through Holy Orders.   There is a unity of mission between the laity and the ministerial priesthood.  

The laity exercise their baptismal priesthood through participation in Christ’s mission as priest, prophet and king.  What does sharing in Christ’s mission as priest, prophet and king mean to the faithful?  A priest fosters holiness, a prophet bears witness to the truth of God, and the people of God share in the royal office of Christ in service, especially to the poor and the suffering.  The common priesthood of the faithful is exercised in a life of faith, hope, and charity.  

The ministerial priesthood is at the service of the common priesthood.  There are two degrees of ministerial participation in the priesthood of Christ: episcopacy (bishops) and presbyterate (priests).  The diaconate is a degree of service.  These three orders are conferred by ordination.  Ordination imprints an indelible (a permanent) sacramental character on the ordained.  

The bishop receives the fullness of the sacrament of Holy Orders.  Priests are united with the bishop from whom they receive the charge of a parish or other church offices.  By virtue of Holy Orders, the priest acts in the person of Christ, in persona Christi Capitis.  This ministerial priesthood is prefigured in the Old Covenant in that the tribe of Levi was set apart for liturgical service.  

Whether we serve in the common priesthood or the ministerial priesthood let all we do be done for the glory of the Lord.