13 Although he was made by God in a state of holiness, from the very onset of his history man abused his liberty, at the urging of the Evil One. Man set himself against God and sought to attain his goal apart from God. Although they knew God, they did not glorify Him as God, but their senseless minds were darkened and they served the creature rather than the Creator. What divine revelation makes known to us agrees with experience. Examining his heart, man finds that he has inclinations toward evil too, and is engulfed by manifold ills which cannot come from his good Creator. Often refusing to acknowledge God as his beginning, man has disrupted also his proper relationship to his own ultimate goal as well as his whole relationship toward himself and others and all created things. Therefore man is split within himself. As a result, all of human life, whether individual or collective, shows itself to be a dramatic struggle between good and evil, between light and darkness. Indeed, man finds that by himself he is incapable of battling the assaults of evil successfully, so that everyone feels as though he is bound by chains. But the Lord Himself came to free and strengthen man, renewing him inwardly and casting out that "prince of this world" (John 12:31) who held him in the bondage of sin. For sin has diminished man, blocking his path to fulfillment. The call to grandeur and the depths of misery, both of which are a part of human experience, find their ultimate and simultaneous explanation in the light of this revelation.
Source: Gaudium et Spes (Vatican.va)