Lumen Gentium

One of the principal documents of the Second Vatican Council, Lumen Gentium is the Dogmatic Constitution of the Church. The name means "light of the world" in Latin and is from the first line of the document, as is customary with Cathoic Church documents. It was approved by the assembled bishops by a vote of 2,151 to 5 and promulgated by Pope Paul VI on November 24, 1964.

One of the key portions of Lumen Gentium is it's second chapter, with it's declaration that the Church was "the People of God":

At all times and in every race God has given welcome to whosoever fears Him and does what is right. God, however, does not make men holy and save them merely as individuals, without bond or link between one another. Rather has it pleased Him to bring men together as one people, a people which acknowledges Him in truth and serves Him in holiness... ...Christ instituted this new covenant, the new testament, that is to say, in His Blood, calling together a people made up of Jew and gentile, making them one, not according to the flesh but in the Spirit. This was to be the new People of God. For those who believe in Christ, who are reborn not from a perishable but from an imperishable seed through the word of the living God, not from the flesh but from water and the Holy Spirit, are finally established as "a chosen race, a royal priesthood, a holy nation, a purchased people . . . who in times past were not a people, but are now the people of God". (LG 9)

Though they differ from one another in essence and not only in degree, the common priesthood of the faithful and the ministerial or hierarchical priesthood are nonetheless interrelated: each of them in its own special way is a participation in the one priesthood of Christ. The ministerial priest, by the sacred power he enjoys, teaches and rules the priestly people; acting in the person of Christ, he makes present the eucharistic sacrifice, and offers it to God in the name of all the people. But the faithful, in virtue of their royal priesthood, join in the offering of the Eucharist. They likewise exercise that priesthood in receiving the sacraments, in prayer and thanksgiving, in the witness of a holy life, and by self-denial and active charity. (LG 10)

This theme was built on in the fifth chapter, "The Universal Call to Holiness":

Thus it is evident to everyone, that all the faithful of Christ of whatever rank or status, are called to the fullness of the Christian life and to the perfection of charity; by this holiness as such a more human manner of living is promoted in this earthly society. In order that the faithful may reach this perfection, they must use their strength accordingly as they have received it, as a gift from Christ. They must follow in His footsteps and conform themselves to His image seeking the will of the Father in all things. They must devote themselves with all their being to the glory of God and the service of their neighbor. In this way, the holiness of the People of God will grow into an abundant harvest of good, as is admirably shown by the life of so many saints in Church history. The classes and duties of life are many, but holiness is one-that sanctity which is cultivated by all who are moved by the Spirit of God, and who obey the voice of the Father and worship God the Father in spirit and in truth. These people follow the poor Christ, the humble and cross-bearing Christ in order to be worthy of being sharers in His glory. Every person must walk unhesitatingly according to his own personal gifts and duties in the path of living faith, which arouses hope and works through charity. (LG 40,41)

In drafting what they called a "constitution" of the Church, the council fathers did not ignore its hierarchical structure. They did try to return to the origins of the hierarchy, the teaching ministry of the original apostles and their helpers:

That divine mission, entrusted by Christ to the apostles, will last until the end of the world,since the Gospel they are to teach is for all time the source of all life for the Church. And for this reason the apostles, appointed as rulers in this society, took care to appoint successors. ... ... Bishops, therefore, with their helpers, the priests and deacons, have taken up the service of the community, presiding in place of God over the flock, whose shepherds they are, as teachers for doctrine, priests for sacred worship, and ministers for governing. And just as the office granted individually to Peter, the first among the apostles, is permanent and is to be transmitted to his successors, so also the apostles' office of nurturing the Church is permanent, and is to be exercised without interruption by the sacred order of bishops. Therefore, the Sacred Council teaches that bishops by divine institution have succeeded to the place of the apostles, as shepherds of the Church, and he who hears them, hears Christ, and he who rejects them, rejects Christ and Him who sent Christ. (LG 20)

Contents

1. The Mystery of the Church
2. The People of God
3. The Hierarchical Structure of the Church and the Episcopate in Particular
4. The Laity
5. The Universal Call to Holiness in the Church
6. Religious
7. The Eschatological Nature of the Pilgrim Church and Its Union with the Church in Heaven
8. The Blessed Virgin Mary, Mother of God, in the Mystery of Christ and of the Church

The full English text is available on the Vatican web site at http://www.vatican.va/archive/hist_councils/ii_vatican_council/documents/vat-ii_const_19641121_lumen-gentium_en