The eternal Father, by a free and hidden plan of His own wisdom and goodness, created the whole world, and chose to raise men to a participation in the divine life. He did not abandon men, fallen in Adam, but ceaselessly offered helps to salvation, in view of Christ, the Redeemer “who is the image of the invisible God, the firstborn of every creature” (Col 1:15). […]
To carry out the will of the Father, Christ inaugurated the Kingdom of Heaven on earth and revealed to us its mystery. By His obedience, He brought about Redemption. The Church, which is the Kingdom of Christ now present in mystery, grows visibly through the power of God in the world. […]
Mission to proclaim and to spread the Kingdom of Christ
The Lord Jesus set the Church on its course by preaching the Good News, that is, the coming of the Kingdom of God, promised for centuries in the Scriptures: “The time is fulfilled, and the Kingdom of God is at hand” (Mk 1:15; cf. Mt 4:17). This Kingdom was made manifest to men in the word, in the works, and in the presence of Christ. The Word of the Lord is compared to a seed sown in a field (cf. Mk 4:14); those who hear it with faith and become part of the little flock of Christ (cf. Lk 12:32), have received the Kingdom itself. Then, by its own power the seed sprouts and grows until harvest time (cf. Mk 4:26-29).
The Miracles of Jesus also confirm that the Kingdom has already arrived on earth: “If I cast out devils by the finger of God, then the Kingdom of God has come upon you” (Lk 11:20; cf. Mt 12:28). But above all, the Kingdom is manifest in the very Person of Christ, the Son of God and the Son of Man, who came “to serve and to give His life as a ransom for many” (Mk 10:45). When Jesus, who had suffered the death of the cross for mankind arose, He appeared as Lord, Christ and eternal Priest (cf. Acts 2:36; Heb 5:6; 7, 17-21), and He poured out on His disciples the Spirit promised by the Father (cf. Acts 2:33).
The Church, equipped with the gifts of its Founder and faithfully guarding His precepts of charity, humility and self-sacrifice, hence receives the mission to proclaim and to spread among all peoples the Kingdom of Christ and of God and to be, on earth, the initial budding forth of that Kingdom. While it slowly grows, it longs for the completed Kingdom and, with all its strength, hopes and desires to be united in glory with its King. […]
“A chosen race, a royal priesthood, a holy nation”
It pleased God, however, not to sanctify and save men as individuals without any mutual connection, but to make of them a people who would acknowledge Him in truth and serve Him in holiness. He therefore chose the race of Israel as a people unto Himself, establishing with it a covenant and progressively instructing it, making Himself and the decree of His will known in its history and rendering it holy unto Himself.
All these things, however, were done in preparation and as a figure of that new and perfect covenant to be ratified in Christ, and of that fuller revelation which was to be given through the Word of God Himself made flesh. “Behold the days shall come saith the Lord, and I will make a new covenant with the House of Israel, and with the house of Judah. […] I will give my law in their bowels, and I will write it in their heart, and I will be their God, and they shall be my people. […] For all of them shall know Me, from the least of them even to the greatest, saith the Lord” (Jer 31:31-34).
Christ instituted this new covenant, that is, the new testament in His Blood (cf. 1 Cor 11:25), 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 (cf. 1 Pt 1:23), not from the flesh but from water and the Holy Spirit (cf. Jn 3:5-6), 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” (1 Pt 2:9-10).
Obligation to be the light of the world and the salt of the earth
That messianic people […] has as its end the Kingdom of God, begun on earth by God Himself, and which must be further extended until being brought to perfection by Him at the end of time, when Christ, our life (cf. Col 3:4) shall appear, and “creation itself will be delivered from its slavery to corruption into the freedom of the glory of the sons of God” (Rom 8:21).
So it is that that messianic people, although it does not actually include all men, and at times may look like a small flock, is nonetheless a lasting and sure seed of unity, hope and salvation for the whole human race. Established by Christ as a communion of life, charity and truth, it is also used by Him as an instrument for the redemption of all, and is sent forth into the whole world as the light of the world and the salt of the earth (cf. Mt 5:13-16). […]
The obligation to spread the Faith is imposed on every disciple of Christ, according to his state. But although all the faithful can baptize, the priest alone can complete the building up of the Body in the Eucharistic Sacrifice. Thus are fulfilled the words of God, spoken through His prophet: “From the rising of the sun until the going down thereof my name is great among the gentiles, and in every place a clean oblation is sacrificed and offered up in my name” (Mal 1:11).
In this way the Church both prays and labours in order that the entire world may become the People of God, the Body of the Lord and the Temple of the Holy Spirit, and that in Christ, the Head of all, all honour and glory may be rendered to the Creator and Father of the Universe. ◊
Excerpts from: ST. PAUL VI.
Dogmatic Constitution Lumen gentium,
of the Second Vatican Council, 21/11/1964