This is a powerful teaching from the Holy Father—in his daily audience of December 3, 2008— about the nature of good and evil and the human soul.
“The Pope explained the importance of distinguishing between two aspects of the theory of original sin, one "an empirical, tangible reality, the other relating to the mystery, the ontological foundation of the event. In effect, there is a contradiction in our being. On the one hand we know we must do good, and in our inner selves this is what we desire, yet at the same time we feel an impulse to do the opposite, to follow the path of egoism, of violence, ... though we know that this means working against good, against God and against our fellow man".
"This inner contradiction of our being is not a theory. We all experience it every day as around us we see the second of these two wills prevail ", he said. "Suffice to think of daily news of injustices, violence, dissipation. This is a fact. From the power evil has over our souls, a foul river of evil has arisen over history, poisoning the human landscape. ... Yet at the same time this contradiction ... in our history arouses the desire for redemption. The truth is that the desire for the world to change, ... for the creation of a world of justice peace and goodness, is present everywhere".
"The power of evil in the heart and history of humankind is undeniable, yet how do we explain it? In the history of thought, discounting Christian faith, there exits one main explanatory model with a number of variants. This model holds that human beings are inherently contradictory: they carry good and evil in themselves. ... Such dualism is insuperable ... and will always be the same".
"In the evolutionist and atheistic view of the world ... it is held that human beings as such have, from the beginning, borne evil and good within themselves. ... Humans are not simply good, but open to good and to evil ... both of them original. Human history then, according to this view, does nothing more than follow the model present in all evolution. What Christians call original sin is only this blend of good and evil".
"This, in the final analysis, is a vision of despair. If it is true, evil is invincible, ... all that counts is individual interest, any form of progress would necessarily be paid for with a river of evil, ... and anyone who wishes to progress would have to pay this price. ... This modern idea, in the end, can create only sadness and cynicism".
"Again we ask ourselves: what does the faith say? ... St. Paul ... confirms the contradiction between the two natures, ... the reality of the darkness of evil weighing upon the whole of creation. Yet, in contrast to the desolation ... of dualism ... and monism, ... the faith speaks to us of two mysteries of light and one of darkness", and the mystery of darkness is "enclosed within in the mysteries of light".
"The faith tells us that there are no two principles, one good and one evil. There is only one principle which is God the Creator and He is solely good, without shadow of evil. Hence, neither are human beings a mix of good and evil. The human being as such is good. ... This is the joyful announcement of the faith: there is but one source, a source of good, the Creator, and for this reason ... life too is good".
"There is also a mystery of darkness, ... which does not arise from the source of being, it is not original. Evil arises from created freedom, a freedom that has been abused. How has this happened? This remains unclear. Evil is not logical. Only God and goodness are logical, only they are light. Evil remains a mystery, ... of itself illogical".
"Evil arises from a subordinate source; God with His light is stronger. For this reason evil can be overcome, for this reason the creature ... is not only curable but is in fact cured. God introduced the cure. He personally entered history and, to counteract the permanent source of evil, placed a source of pure good: Christ crucified and risen, the New Adam Who opposes the foul river of evil with a river of light ... that remains present in history".