"The Christian faithful are those who, inasmuch as they have been incorporated in Christ through Baptism, have been constituted as the people of God; for this reason, since they have become sharers in Christ's priestly, prophetic, and royal office in their own manner, they are called to exercise the mission which God has entrusted to the Church to fulfill in the world, in accord with the condition proper to each one. In virtue of their rebirth in Christ there exists among all the Christian faithful a true equality with regard to dignity and the activity whereby all cooperate in the building up of the Body of Christ in accord with each one's own condition and function."
The very differences which the Lord has willed to put between the members of his body serve its unity and mission. For "in the Church there is diversity of ministry but unity of mission. To the apostles and their successors Christ has entrusted the office of teaching, sanctifying and governing in his name and by his power. But the laity are made to share in the priestly, prophetical, and kingly office of Christ; they have therefore, in the Church and in the world, their own assignment in the mission of the whole People of God." Finally, "from both groups [hierarchy and laity] there exist Christian faithful who are consecrated to God in their own special manner and serve the salvific mission of the Church through the profession of the evangelical counsels
-Catechism of the Catholic Church, 871-874