Apostolicam Actuositatem section 2 begins:
The Church was founded for the purpose of spreading the kingdom of Christ throughout the earth for the glory of God the Father, to enable all … to share in His saving redemption, and that through them the whole world might enter into a relationship with Christ.
The document further defines “apostolate” as “all activity of the Mystical Body directed to the attainment of this goal,” and is the action of every member of the Church. Yet another blow to those who would prefer a smaller, more “orthodox” Church. The very nature of a living body demands growth, and all members are obliged by baptism to participate in such growth.
Indeed, the organic union in this body and the structure of the members are so compact that the member who fails to make his proper contribution to the development of the Church must be said to be useful neither to the Church nor to himself.
“Development” implies a forward movement, an effort to evolve from bad to good, from good to better, etc.. The strong implication is that the Church is a work in progress, incomplete, not yet having achieved the universal salvation envisioned by the Council. And not only the Council, but Jesus: “Go, therefore, and make disciples of all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Spirit” (Matt 28:19). And not only Jesus, but the Jewish prophetic tradition as described by Isaiah (25:6-8a): “On this mountain the Lord of hosts will provide for all peoples A feast of rich food and choice wines, juicy, rich food and pure, choice wines. On this mountain he will destroy the veil that veils all peoples, The web that is woven over all nations; he will destroy death forever.“
AA continues, noting “a diversity of ministry but a oneness of mission.” Too often we get caught up in the hierarchical diversity: pope, bishops, priests, laity. But diversity of ministry also exists among various categories of people. Other Vatican II documents stress the need for teamwork among bishops, priests. It shouldn’t be wildly crazy to suggest lay people need to uncover a unitive mission as they cross ideological lines to further the development of the Church.
Lay people share in mission of the apostles:
Christ conferred on the Apostles and their successors the duty of teaching, sanctifying, and ruling in His name and power. But the laity likewise share in the priestly, prophetic, and royal office of Christ and therefore have their own share in the mission of the whole people of God in the Church and in the world.