Isaac spoke to his father Abraham. “Father!” he said. “Here I am,” he replied. Isaac continued, “Here are the fire and the wood, but where is the sheep for the burnt offering?” “My son,” Abraham answered, “God will provide the sheep for the burnt offering.”
Genesis 22:7-8

613 Christ's death is both the Paschal sacrifice that accomplishes the definitive redemption of men, through "the Lamb of God, who takes away the sin of the world", and the sacrifice of the New Covenant, which restores man to communion with God by reconciling him to God through the "blood of the covenant, which was poured out for many for the forgiveness of sins".

614 This sacrifice of Christ is unique; it completes and surpasses all other sacrifices.  First, it is a gift from God the Father himself, for the Father handed his Son over to sinners in order to reconcile us with himself. At the same time it is the offering of the Son of God made man, who in freedom and love offered his life to his Father through the Holy Spirit in reparation for our disobedience.

615 "For as by one man's disobedience many were made sinners, so by one man's obedience many will be made righteous."  By his obedience unto death, Jesus accomplished the substitution of the suffering Servant, who "makes himself an offering for sin", when "he bore the sin of many", and who "shall make many to be accounted righteous", for "he shall bear their iniquities".  Jesus atoned for our faults and made satisfaction for our sins to the Father.