I believe that the sacrifice that Christ offered on the cross (Himself)was the perfect sacrifice and yet I hear that there is something added to that sacrifice during the Eucharistic prayer that completes what was lacking on Calvary. Is this true?
There was nothing “lacking” on Calvary, except for
us. We weren’t there. During the Holy Sacrifice of the Mass, Calvary is re-presented, in an unbloody manner: the bread is consecrated and changed, by God, into the Body of Christ, and the wine is consecrated and changed, by God, into the Blood of Christ. These are done
separately as a sign that Jesus truly died, and because the Eucharist is a re-presentation of that sacrifice, and it is a sign of the blood flowing from the side of Christ. However, once the consecration is complete, the Body, Blood, Soul, and Divinity of Jesus Christ is wholly present under both the appearances of the bread and the wine (meaning that even a crumb of what appears to be bread, or a drop of what appears to be wine, contains Jesus, whole and entire). This union is shown by the mingling of a portion of the Host with the Chalice: the priest takes a small piece of a Host and places it in the Chalice, thus signifying the eternal union of Jesus’ whole person (Body, Blood, Soul, and Divinity).
What exactly is sacrificed during the Eucharistic prayer? Christ? …the bread and wine? …the faithful taking part in the Mass?
Well, let’s step back a bit.
FIRST,
bread and wine is offered to God, and the priest asks Him to find favor with our offering and deem it acceptable to
become the Body and Blood of our Lord. (This is the Offertory.)
SECOND, the priest asks the faithful to “pray that
my sacrifice and yours may be acceptable to God”. The Eucharistic sacrifice is offered at the hands of the priest; what is
our sacrifice? Well, we offer the Eucharist
through the priest, but also (in a way)
with the priest, and that is exemplified by our desire to unite ourselves to Christ as he offers himself to the Father. (This is at the end of the Offertory.)
THIRD, the priest asks God the Father to send His Holy Spirit upon the offerings of bread and wine and change them into the Body and Blood of His Son, our Lord Jesus Christ. (This is the
Epiclesis of the Eucharistic Prayer.)
FOURTH, the bread and wine are consecrated by God through the hands of the priest speaking the words of Jesus. This grace is granted only to the priest; the people do not have the power to “confect” the Sacrament. (This is the Consecration of the Eucharistic Prayer.)
FIFTH, after the consecration of the bread and wine has taken place,
the priest then offers the Eucharist – which is our very Lord and Savior – to the Father.
This is where our sharing in the priesthood of Christ is displayed: we offer the Eucharist to the Father as well, and we strive to unite ourselves to it. See, what Jesus offered to the Father was nothing less than himself; a lamb or a bull would not suffice. Since Jesus is the perfect sacrifice, we cannot offer God anything better than him…
but we can offer
along with Jesus ourselves after the model of Jesus, not as a bloody sacrifice, but as a
living sacrifice of praise. This sacrifice of ourselves to God has merit only insofar as it is united with the perfect sacrifice of Jesus. (This is the Offering of the Eucharistic Prayer.)
For more on this manner of sharing in the offering of the Eucharist to God, read
this post of mine from another forum.
If Christ died once for all, why is His sacrifice “re-presented” at every Mass?
Because at Mass, the veil between heaven and earth is lifted, and we are taking part in the heavenly eternal liturgy. See Rev. 4-5, where Jesus is seen by St. John as “a
Lamb,
standing as though
slain”. That description is a paradox: a slain animal does not
stand! But Jesus, in heaven, is seen with the marks of his crucifixion and death, and yet stands, having gloriously conquered sin, death, and the grave. Furthermore, we know from the Letter to the Hebrews that Jesus is forever interceding at the right hand of the Father. He is not
sacrificing himself again, but he is
presenting himself eternally. When we celebrate the Mass and we enter into the Holy Sacrifice, we are witnessing what took place
once in history – the immolation (crucifixion) of our Lord on the cross – as well as what happens forever in heaven – the oblation (presentation) of the Son to the Father.
As for why we cannot merely offer the Eucharist (as Jesus’ flesh and blood) to the Father at Mass
without re-presenting his sacrificial death, the reason is because of the manner by which the Lord himself instituted the Eucharist. He spoke in the present tense: “This is my body which
is given for you.” (Luke 22:19) “This cup which
is poured out for you is the new covenant in my blood.” (Luke 22:20) If what he called his body and blood at the Last Supper were merely symbols (that is, still bread and wine), then he had not yet actually instituted a new covenant with them, since his body was not yet handed over, nor his blood shed. But this is not the case; as the Catholic Church teaches, when Jesus said the bread was his body, it became his body, and the wine in the chalice became his blood, and the sacrifice was
made present to the apostles as it is made present to us (with one difference: for them, it was made present before it happened in time; for us, it is made present after it happened in time). In other words, the Body and Blood of our Lord cannot be made present without it being an unbloody presentation of his body
given for us and his blood
shed for us.