PRIESTHOOD OF JESUS CHRIST
The whole Church is called a priestly people because we are all baptized into the three munera or offices of Christ as priest, prophet and king. Lay Catholics participate in the priesthood of Christ, which is called the “common priesthood of the faithful,” by offering spiritual sacrifices acceptable to the Father (cf. 1 Peter 2:5, Rom 12:1) and in witnessing to the Good News of Jesus Christ in the world. On the other hand, the “ministerial priesthood” is reserved for those men whom the Church discerns as called by God for priestly service in the Church. The priest shares in the bishop’s ministry of sanctifying, teaching, and governing. The priest never acts according to his own authority, but only by that authority given by God through the hands of the bishop, i.e., the authority of Jesus Christ.
The ministerial priesthood finds its roots in the Old Testament (OT). A priest from the OT is one who offers sacrifices to God on behalf of the people to atone for sins against the covenant. The chosen people of Israel are called a “kingdom of priests and a holy nation” (Ex 19:6; Isa 61:6). But within the people of Israel God chose Levi, one of the twelve tribes, to be set aside for liturgical priestly service. In fact when the angel appeared to Zechariah to tell him that his barren wife Elizabeth would conceive a child (John the Baptist), he was ministering as a priest offering incense (cf. Luke 1:5ff). It was common for those of the tribe of Levi to take turns ministering in the temple as priests.