A sacrifice is a holy act, offered to the Father, by which we are drawn into the life of God. The sacrifices of the Old Testament never fully achieved this purpose. The prophets looked forward to a perfect sacrifice, offered from the rising of the sun to its setting, which would give true glory to God in reparation for our sins.
On the cross, Our Lord offered this perfect sacrifice. His perfect goodness both as God and man made it inevitable that sinful men would hate Him and seek to destroy Him. Many saints have followed in the footsteps of Christ in this respect. Our Lord chose freely to be the suffering servant of the Father because He loved us.
In offering His life on the Cross, Our Lord was the unique mediator between God and man: the perfect priest who could offer the acceptable sacrifice which indeed achieved our reconciliation with God. His prayer for our forgiveness was heard because it was the perfect prayer of God made man.
This one perfect sacrifice is made present at every Mass. The same priest, Jesus Christ, acting through the unworthy hands of the priest at the altar, makes present on that very altar the sacrifice of Himself as a pure, holy, and spotless victim offered to the majesty of the Father, and bringing us everlasting salvation.
At Mass, we are at Calvary, present at the one supreme sacrifice which achieved our eternal redemption. This is the greatest of all gifts that God could give us. The last weeks of Lent give us an opportunity to renew our faith in the mystery of our redemption and to come to the Cross with renewed devotion and love.