The salvation of humanity by Jesus Christ. Literally, to redeem means to free or buy back. Humanity was held captive in that it was enslaved by sin. Since the devil overcame human beings by inducing them to sin, they were said to be in bondage to the devil. Moreover, the human race was held captive as to debt of punishment, to the payment of which it was bound by divine justice.
On all these counts, the Passion of Christ was sufficient and superabundant satisfaction for human guilt and the consequent debt of punishment. His Passion was a kind of price or ransom that paid the cost of freeing humanity from both obligations. Christ rendered satisfaction, not by giving money, but by spending what was of the highest value. He gave himself, and therefore his Passion is called humanity's Redemption. (Etym. Latin redemtio, a buying back, ransoming, redemption.)