Lumen Gentium Ch. 1 - "The Mystery of the Church" - Second Vatican Council

Lumen Gentium is the dogmatic constitution on the Church. There are only two dogmatic constitutions from Vatican II, this and Dei Verbum. Hence this is going to express the core of what Vatican II wanted to communicate. Chapter I is entitled "The Mystery of the Church". 

Goal of the Document 

Paragraph one makes clear the overall goal of the document, which is to show the Church as the sacrament of Christ to the world. This is particularly important because the Church is responsible for this age between the end of public revelation and the Second Coming of Christ at the end of time. The Church is the visible image of God on earth by which man is saved and receives God's grace. And so the goal is to reveal the "... inner nature and universal mission" of the Church to the world today. "...the Church is in Christ like a sacrament or as a sign and instrument both of a very closely knit union with God and of the unity of the whole human race..." The document notes how man is much more closely tied together today by technology. 

Salvation History 

Paragraphs two through five give a historical overview of the Church from God's chosen people, the Israelites, in the Old Testament, to Christ's coming, to the birth of the Church at Pentecost, to the end of time. "While it slowly grows, the Church strains toward the completed Kingdom and, with all its strength, hopes and desires to be united in glory with its King." 

Symbols of the Church 

The document then draws on typological images from the Old Testament which teach us about the Church. These are "tending sheep or cultivating the land, from building or even from family life and betrothals...".

The sheepfold -

The cultivated vineyard -

The temple -

A mother -

The Mystical Body of Christ 

The image par excellence, though, is the Church as the mystical body of Christ. All the baptized are united into the body as one of its members. These members have their own roles and functions in the body, but when the body is harmed or helped in one part it radiates to the whole of the body. Ultimately, though, Christ is the head of the body and the Church is the body. Thus the Church participates in Christ's mediatorial role to the Father. 

Also, importantly, the Christ's body is not just those in Heaven or those on earth, but the Church extends to all those in his body both in Heaven, in Purgatory, and on earth - the Church triumphant, suffering, and militant. "... the society structured with hierarchical organs and the Mystical Body of Christ, are not to be considered as two realities, nor are the visible assembly and the spiritual community, nor the earthly Church and the Church enriched with heavenly things; rather they form one complex reality which coalesces from a divine and a human element." 

Church's Main Focus 

Chapter one ends by speaking of the Church's main mission. The Church indeed does seek to help the poor and to reduce human suffering in the world, but its main focus has to be the salvation of souls.