§ 1850 Sin is … a revolt against God.
See the Fall of Adam for the Catechism § 396-401 on original sin.
The traditional Catholic description of the stain of original sin is that it darkens our intellect and weakens our will. St. Thomas Aquinas, in his Summa Theologica, ST I-II, 85, 3 explains man’s loss of original justice as four wounds, weakening of the four cardinal virtues: prudence, justice, fortitude and temperance.
St. Thomas makes clear that the stain of original sin is a weakening, not a total loss. With God’s grace, we can through radical transformation overcome the stain of original sin and, at the end of our earthy lives, return to paradise. We sing in the Easter Vigil Mass’ Exsultet 11:20, the original sin is a felix culpa, a happy fault, in that God’s infinite love for us has given us a redemption infinitely greater than Eden.