19 The Church has, therefore, in common with the Word Incarnate the aim, the obligation and the function of teaching all men the truth, of governing and directing them aright, of offering to God the pleasing and acceptable sacrifice; in this way the Church re-establishes between the Creator and His creatures that unity and harmony to which the Apostle of the Gentiles alludes in these words: "Now, therefore, you are no more strangers and foreigners; but you are fellow citizens with the saints and domestics of God, built upon the foundation of the apostles and prophets, Jesus Christ Himself being the chief corner-stone; in whom all the building, being framed together, groweth up into a holy temple in the Lord, in whom you also are built together in a habitation of God in the Spirit." Thus the society founded by the divine Redeemer, whether in her doctrine and government, or in the sacrifice and sacraments instituted by Him, or finally, in the ministry, which He has confided to her charge with the outpouring of His prayer and the shedding of His blood, has no other goal or purpose than to increase ever in strength and unity.
Source: Mediator Dei (Vatican.va)