Christ’s death is the unique and definitive sacrifice
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”.
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.
Jesus substitutes his obedience for our disobedience
“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.
Jesus consummates his sacrifice on the cross
It is love “to the end” that confers on Christ’s sacrifice its value as redemption and reparation, as atonement and satisfaction. He knew and loved us all when he offered his life. Now “the love of Christ controls us, because we are convinced that one has died for all; therefore all have died.” No man, not even the holiest, was ever able to take on himself the sins of all men and offer himself as a sacrifice for all. The existence in Christ of the divine person of the Son, who at once surpasses and embraces all human persons, and constitutes himself as the Head of all mankind, makes possible his redemptive sacrifice for all.
The Council of Trent emphasizes the unique character of Christ’s sacrifice as “the source of eternal salvation” and teaches that “his most holy Passion on the wood of the cross merited justification for us.” And the Church venerates his cross as she sings: “Hail, O Cross, our only hope.”
Our participation in Christ’s sacrifice
The cross is the unique sacrifice of Christ, the “one mediator between God and men”. But because in his incarnate divine person he has in some way united himself to every man, “the possibility of being made partners, in a way known to God, in the paschal mystery” is offered to all men. He calls his disciples to “take up [their] cross and follow [him]”, for “Christ also suffered for [us], leaving [us] an example so that [we] should follow in his steps.” In fact Jesus desires to associate with his redeeming sacrifice those who were to be its first beneficiaries. This is achieved supremely in the case of his mother, who was associated more intimately than any other person in the mystery of his redemptive suffering.
Apart from the cross there is no other ladder by which we may get to heaven.