Important Message From Vatican II
For a monumental struggle against the powers of darkness pervades the whole history of man. The battle was joined from the very origins of the world and will continue until the last day, as the Lord has attested.(8) Caught in this conflict, man is obliged to wrestle constantly if he is to cling to what is good, nor can he achieve his own integrity without great efforts and the help of God's grace.
That is why Christ's Church, trusting in the design of the Creator, acknowledges that human progress can serve man's true happiness, yet she cannot help echoing the Apostle's warning: "Be not conformed to this world" (Rom. 12:2). Here by the world is meant that spirit of vanity and malice which transforms into an instrument of sin those human energies intended for the service of God and man.
Hence if anyone wants to know how this unhappy situation can be overcome, Christians will tell him that all human activity, constantly imperiled by man's pride and deranged self-love, must be purified and perfected by the power of Christ's cross and resurrection. For redeemed by Christ and made a new creature in the Holy Spirit, man is able to love the things themselves created by God, and ought to do so. He can receive them from God and respect and reverence them as flowing constantly from the hand of God. Grateful to his Benefactor for these creatures, using and enjoying them in detachment and liberty of spirit, man is led forward into a true possession of them, as having nothing, yet possessing all things.(9) "All are yours, and you are Christ's, and Christ is God's" (1 Cor. 3:22-23).
38. For God's Word, through Whom all things were made, was Himself made flesh and dwelt on the earth of men.(10) Thus He entered the world's history as a perfect man, taking that history up into Himself and summarizing it.(11) 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 worlds 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,(12) 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,(13) 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.(14)
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.
from Gaudium et Spes from the Second Vatican Council #'s 37-38