How does the Catholic Church understand the priesthood of all believers? In the process of answering a question on the Sacraments, I discovered that Catholic Church accepts the doctrine of the "priesthood of all believers".  This rather surprised me since the Church has separate, ordained priests who, among other things, perform the Sacraments.  From my point of view (as an Evangelical Protestant), passages such as:


  But you are a chosen race, a kingdom of priests, a holy nation, a people to be a personal possession to sing the praises of God who called you out of the darkness into his wonderful light.&mdash;1st Peter 2:9 (NJB)


...suggest that everyone in the church has a duty to stand before God.  Practically the entire book of Hebrews makes the case that the Old Testament model of priests as holy (literally, "set apart") men has been replaced by a new model in which we all function as priests.

At a very simple level, it seems impossible to hold both of the following statements as true:


The entire Church is set apart by God to be priests.
Individuals are set apart from the rest of the Church by God to be priests.


Am I equivocating on the word "priest"?  (Or to put it another way, are there two different classes of priests in the Catholic Church?)
The Catholic Church believes in three different types of priests: (Edited from this Wikipedia article.)

first, the priesthood of all believers (1 Peter 2:5–9);
second, the ordained priesthood (Acts 14:23, Romans 15:16, Titus 1:5); and
third, the high priesthood of Jesus (Hebrews 3:1).

The Catholic Church accepts the 'priesthood of all believers' doctrine. This is exemplified in the 'Chaplet of Divine Mercy' prayer (which I personally believe to be a very powerful form of prayer), in which the individual Christian declares: &quot;Eternal Father, I offer you the Body and Blood, Soul and Divinity, of your dearly beloved Son, our Lord Jesus Christ, in atonement for our sins...&quot;
As Christians, we are all called to evangelize - to spread the love of God, and we have a responsibility towards the preservation and propagation of the faith.
God also chooses a few among us to be 'fishers of men', and these are called to serve as ordained priests through apostolic succession.

So what sacrifice does the priesthood of the laity offer?  What do we lay “priests” consecrate?
St. Paul answers the first question in Romans 12:2: “offer your bodies as a living sacrifice holy and acceptable to God, your spiritual worship.”  As the Lord Jesus offered himself totally for our sake, we are called to lay down our lives for Him and for one another.  In rare occasions, this may mean the “supreme sacrifice” of martyrdom.  But more commonly, it means the living sacrifice, the “white martyrdom,” of denying our own will to embrace His will, “offering up” in love the work we do and the trials we endure, as a sacrifice of praise of God and intercession for others in need.  Studying for exams, changing a soiled diaper, going to work to provide for our families--these are all activities that become opportunities for Christians to exercise their sacred priesthood.  In fact during the Sunday Eucharist, as the bread and wine are carried up to the altar, we are called to consciously place ourselves and all sacrifices of the past week on the altar with the gifts to be united with Christ’s perfect sacrifice to the Father.
So what do we lay “priests” consecrate?  Vatican II gives us the answer to that question in its Decree on the Apostolate of the Laity.  We are called to consecrate the secular, the earthy, the nitty-gritty realities of life to God.  When we give thanks over a meal, we consecrate it to God’s glory and sanctify it.  When we offer our work in sacrifice, and live out our Christian witness in the workplace, we consecrate our work and sanctify it.  We lay priests are to be God’s secret agents in every arena of life, in places where ministerial priests and religious may never go, elevating, purifying, sanctifying, blessing.
(from Priesthood of Believers By: Dr. Marcellino D'Ambrosio | The Crossroads Initiative.)

PS: This is an interesting read - THE PRIESTHOOD DEBATE, James Akin | EWTN.