An excerpt from the pastoral constitution on the Church in the modern world from the Second Vatican Council.
Summary: God entered into His creation and offers the Holy Spirit and the Eucharist to transform and purify us, so that the effort to establish peace, justice, and universal brotherhood is not a hopeless one (§ 38). Somebody all Creation will be renewed in Christ and His Kingdom will be fully manifested, but until then the expectation of a new earth must not weaken but rather stimulate our concern for cultivating this one (§ 39).
38. For God’s Word, through Whom all things were made, was Himself made flesh and dwelt on the earth of men.  Thus He entered the world’s history as a perfect man, taking that history up into Himself and summarizing it.  He Himself revealed to us that “God is love” (1 John 4:8) and at the same time taught us that the new command of love was the basic law of human perfection and hence of the world’s transformation.
To those, therefore, who believe in divine love, He gives assurance that the way of love lies open to men and that the effort to establish a universal brotherhood is not a hopeless one. He cautions them at the same time that this charity is not something to be reserved for important matters, but must be pursued chiefly in the ordinary circumstances of life. Undergoing death itself for all of us sinners,  He taught us by example that we too must shoulder that cross which the world and the flesh inflict upon those who search after peace and justice. Appointed Lord by His resurrection and given plenary power in heaven and on earth,  Christ is now at work in the hearts of men through the energy of His Holy Spirit, arousing not only a desire for the age to come, but by that very fact animating, purifying and strengthening those noble longings too by which the human family makes its life more human and strives to render the whole earth submissive to this goal.
Now, the gifts of the Spirit are diverse: while He calls some to give clear witness to the desire for a heavenly home and to keep that desire green among the human family, He summons others to dedicate themselves to the earthly service of men and to make ready the material of the celestial realm by this ministry of theirs. Yet He frees all of them so that by putting aside love of self and bringing all earthly resources into the service of human life they can devote themselves to that future when humanity itself will become an offering accepted by God. 
The Lord left behind a pledge of this hope and strength for life’s journey in that sacrament of faith where natural elements refined by man are gloriously changed into His Body and Blood, providing a meal of brotherly solidarity and a foretaste of the heavenly banquet.
39. We do not know the time for the consummation of the earth and of humanity,  nor do we know how all things will be transformed. As deformed by sin, the shape of this world will pass away;  but we are taught that God is preparing a new dwelling place and a new earth where justice will abide,  and whose blessedness will answer and surpass all the longings for peace which spring up in the human heart.  Then, with death overcome, the sons of God will be raised up in Christ, and what was sown in weakness and corruption will be invested with incorruptibility.  Enduring with charity and its fruits,  all that creation  which God made on man’s account will be unchained from the bondage of vanity.
Therefore, while we are warned that it profits a man nothing if he gain the whole world and lose himself,  the expectation of a new earth must not weaken but rather stimulate our concern for cultivating this one. For here grows the body of a new human family, a body which even now is able to give some kind of foreshadowing of the new age.
Hence, while earthly progress must be carefully distinguished from the growth of Christ’s kingdom, to the extent that the former can contribute to the better ordering of human society, it is of vital concern to the Kingdom of God. 
For after we have obeyed the Lord, and in His Spirit nurtured on earth the values of human dignity, brotherhood and freedom, and indeed all the good fruits of our nature and enterprise, we will find them again, but freed of stain, burnished and transfigured, when Christ hands over to the Father: “a kingdom eternal and universal, a kingdom of truth and life, of holiness and grace, of justice, love and peace.”  On this earth that Kingdom is already present in mystery. When the Lord returns it will be brought into full flower.
- Cf. John 1:3 and 14.
- Cf. Eph. 1:10.
- Cf. John 3:16; Rom. 5:8.
- Cf. Acts 2:36; Matt. 28:18.
- Cf. Rom. 15:16.
- Cf. Acts 1:7.
- Cf. 1 Cor. 7:31; St. Irenaeus, Adversus haereses, V, 36, PG, VIII, 1221.
- Cf. 2 Cor. 5:2; 2 Pet. 3:13.
- Cf. 1 Cor. 2:9; Apoc. 21:4-5.
- Cf. 1 Cor. 15:42 and 53.
- Cf. 1 Cor. 13:8; 3:14.
- Cf. Rom. 8:19-21.
- Cf. Luke 9:25.
- Cf. Pius XI, encyclical letter Quadragesimo Anno: AAS 23 (1931), p. 207.
- Preface of the Feast of Christ the King.