The priest completes the consecration of the wine with these words:

The Mass is the reenactment of Christ's Sacrifice is not only as the memory of a past event but the actualization, here and now, of this One Sacrifice for all mankind. That this makes present the death of Christ on the Cross is evident in the words of consecration: "This is my body" and "This is the cup of my blood". The two are consecrated separately to signify the separation of the blood from Christ's body.

Christ died physically only once but the sacrifice which is now an integral part of his risen humanity must be actualized, made present, in history. A sacrifice is an offering made to God, thus Christ offered his life to the Father for the forgiveness of sins. Through the sacrifice of Christ in the Eucharist we offer our lives, that is, our praise, suffering, prayers and work to the Father in the Spirit, thus our lives become sacrificial, an offering pleasing to the Father.

We offer Christ's Sacrifice in union with the Saints of Heaven and also for those who have died in Christ and are now suffering for their sins. The realization of the Eucharistic benefits the souls who have died was profoundly expressed by St. Monica as she was dying in 387 AD to her two sons, Augustine and his brother. She told them,

"Lay ... this body anywhere; ...
this only I request,
that you would remember me in the Lord's altar,
wherever you may be."

(St. Augustie, Confessions, IX, 11, 27)

Because the sacrifice of Christ is the perfect gift to God of infinite value, the Mass is also a sacrifice of offering of praise, thanksgiving, propitiation and petition. Unfortunately our Protestant brothers do not regard the Mass as a sacrifice. "As Luther said, 'The Mass is not a sacrifice... call it benediction, Eucharist, the Lord's table, the Lord's Supper, Memory of the Lord or whatever you like, just so long as you do not dirty it with the name of a sacrifice or action.' "

Tran-substantiation