But, by thinking, praying, and puzzling out some of these mysteries, we can say some more things about them than that - "we don't know and we can't know". This business of "re-presentation" is one of these mysteries that time, prayer, and thought have opened up a little.
Protestants often mistakenly believe that Catholics are repeating Christ's sacrifice at every Mass, in contradiction of 1 Peter 3:18
Because Christ also died once for our sins, the just for the unjust: that he might offer us to God, being put to death indeed in the flesh, but enlivened in the spiritThis is why careful catechists always say "re-presents", clearly pronouncing each side of the hyphenated term: "re" <pause> "presents". As in, "makes present once again." And this isn't a foreign concept to most people - a common home video re-presents your child's 8th birthday party; a favorite photo album re-presents the memories of a great vacation.
So are we saying that in the Holy Mass, we are "reenacting" Christ's sacrifice? Presenting it in the distant way a photo re-presents a memory? Well, if Christ were simply a man, then I believe the answer would be, "yes".
But, of course, we know that Christ was both fully God and fully man. And this alters the equation. Theologists say that the actions of Christ were "theandric" - a Greek term that means "actions of the God-Man (theos = God, andros = man in Greek). So the sacrifice of Jesus on the Holy Cross to redeem us was a theandric action - it contained human properties (such as pain, suffering, and death) and God-based properties.
One of the key properties of God - one that I trip over all the time - is that God exists separate from time. He is not bound by the way His created world works - He exists both within and outside of time. As a theandric action, the sacrifice of Calvary also, in a mysterious way, exists outside of time. In this sense, Christ's sacrifice, while occurring at a specific place at a specific time, also exists in all places at all times, by virtue of the theandric action of Christ.
Does this make your head hurt? Good - because it is supposed to. It is a mystery of God that only He understands fully - but - that doesn't make it any less true. It is this fact that allows an ordained priest or bishop of the Catholic Church to reach across time and space and truly make present again the sacrifice of Our Lord on the altar during Holy Mass. When we see the Body of Christ lifted up by the priest at Mass, we are actually seeing the crucified Christ, lifted up for our sins on His Cross.
As Bishop Sheen famously said, "If you want to see a miracle, go to Mass."