“The Son of Man must suffer"

and be killed

-- Lk 9:22-25

After that first sin, the world is virtually inundated by sin. There is Cain's murder of his brother Abel and the universal corruption which follows in the wake of sin. Likewise, sin frequently manifests itself in the history of Israel, especially as infidelity to the God of the Covenant and as transgression of the Law of Moses. And even after Christ's atonement, sin raises its head in countless ways among Christians. Scripture and the Church's Tradition continually recall the presence and universality of sin in man's history:

What Revelation makes known to us is confirmed by our own experience. For when man looks into his own heart he finds that he is drawn towards what is wrong and sunk in many evils which cannot come from his good creator. Often refusing to acknowledge God as his source, man has also upset the relationship which should link him to his last end, and at the same time he has broken the right order that should reign within himself as well as between himself and other men and all creatures.

-- CCC 401