Sin and Grace
From the Catechism of the Catholic Church, Simplified
Understanding Sin (386-387)
Human history is filled with sin. By understanding the profound relationship of man to God the evil of sin is unmasked.
Without the clarity of the Bible, we would explain sin as a weakness, a mistake or a necessary consequence of a poor social structure. By knowing God's plan, we can see that sin is really man's abuse of his freedom.
Adam and Christ (388-389)
Israel could never grasp the ultimate meaning of the story of Adam and Eve. They knew Adam (the source of sin) but not Christ (the source of grace). Only the Holy Spirit would "convict the world in regard to sin and righteousness and condemnation" (Jn 16:8).
This doctrine of original sin is the "reverse side" of the Good News. Jesus is our Savior because all men need to be saved. Tampering with the doctrine of original sin will undermine the mystery of Christ.
Human History and the Fall (390)
Although using figurative language, the story of Adam's sin does describe an event which took place at the beginning of human history. All human history is marked by that fall of our first parents.
A Prior Fall - Satan (391)
Man's fall contains a "seductive voice," the voice of a fallen angel called "Satan" or the "devil." The Church teaches that Satan and other demons were created "good by God but they became evil by their own doing" (Fourth Lateran Council).
A Free Irrevocable Choice (392-393)
These demons made a free irrevocable choice to reject God. This rebellion is reflected in the tempter's words, "You will be like God" (Gen 3:5). Having sinned from the beginning, the devil is now "the father of lies" (Jn 8:44).
God's mercy toward these fallen angels is useless. Their sin is unforgivable because their choice is irrevocable. "There is no repentance for the angels, just as there is no repentance for men after death" (St. John Damascene).
Disastrous Influence (394-395)
Because of the devil's disastrous influence, Jesus came to earth "to destroy the works of the devil" (1 Jn 3:8), especially his power to seduce man to disobedience.
Satan's power is not infinite and he cannot prevent the building up of God's kingdom. Although Satan can cause grave injuries (both spiritual and physical) God still guides all human history. Why God permits demonic activity is a mystery. "We know that in everything God works for good with those who love him" (Rom 8:28).