Question: A friend says that we are wrong to call the Mass a "sacrifice." The Lord's Supper was just that, a supper for Christ and His Apostles, and not a sacrifice. To use an altar, ritual gestures, and a dead language detracts from the atmosphere of a supper. "Besides," he asks, "how can we add to the sacrifice that Christ offered on the cross"?
Answer: Your friend is quite correct in saying that the Mass is based upon the Last Supper. It might help him to understand the Mass if he knew that the Last Supper was also the Jewish Passover supper (c.f. Matthew xxvi). The Passover was not just a meal. It was kept according to ritual prescription by religious Jews since the time of the Exodus from Egypt. The Passover supper was a meal in which a sacrificial lamb for each household was "slaughtered during the evening twilight.... That same night they shall eat its roasted flesh with unleavened bread and bitter herbs. [W]hatever is left over in the morning shall be burned up." The lambs were slaughtered "as Passover victims" (Exodus xii).
God commanded the Jews to observe the Passover each year, not simply as a holiday dinner, but "as a perpetual ordinance for yourselves and your descendants. Thus, you must observe this rite when you have entered the land promised by the Lord." God leaves no doubt about the nature of this annual ritual when He says, "This is the Passover sacrifice of the Lord...." The sacrificial blood of the lamb protected the homes of the Israelites from the Angel of Death, who destroyed the firstborn in all the unprotected houses of the Egyptians (ibid.).
As a solemn ritual sacrifice, the Passover celebration was conducted in Hebrew; a dead language by the time of Christ, who spoke the Aramaic language with His disciples. Even today, pious Jews follow this tradition. The Passover ritual book (Haggadah) is often available in grocery stores, published by those who market kosher foods. These books contain the rite in both English and Hebrew, with some printing the Hebrew words in Roman letters for those Jews unable to read the Hebrew characters.
The Last Supper, then, was a ritual sacrifice offered in a language reserved for worship. In keeping with Jewish table custom, our Lord and the Apostles sat together on one side of the table, facing east as altars are oriented today.
The Last Supper's significant deviation from the Passover rite occurred as our Lord took the unleavened bread, saying, "This is my body, which is being given for you." And again, after the supper, He took one of the ritual cups of wine, saying, "This cup is the new covenant in my blood, which shall be shed for you." (Luke xxii) Almost immediately after ordering them to perform this same sacrificial ritual in His name and in memory of Him, He quite literally gave over His body to the power of the soldiers -- and within less than a day, He quite literally poured out His blood in the sacrifice of the cross. The sacrifice of the Old Law gave way to the perpetual sacrifice of the New Law of Grace.
The Apostles understood that our Lord was speaking literally even before He was taken by the soldiers. A year previously, during the same Passover time, after miraculously feeding a crowd of five thousand with a few loaves of bread, Jesus insistently stated that He was going to give His followers His flesh and blood to drink as necessary nourishment. (John vi) Many of His disciples protested that this was impossible even for Him to do, and they turned their backs and left Him. And our Lord did not call them back. He could have recovered His following by telling them that they misunderstood; that He only meant that He would give them a symbol of His body and blood. He did not call them back because He meant what He said quite literally -- that when He or His Apostles performed the sacrificial ritual they would distribute His true body and blood -- that in diverse times and places the sacrifice of the cross would be made present on the altars of His faithful.
The necessity of receiving our Lord's body and blood -- "unless you eat the flesh of the Son of Man, and drink His blood, you shall not have life in you" -- clearly demonstrates that the sacrifice of the Last Supper did not end after one meal in the upper room. The Apostles, and the priests they ordained, followed our Lord's command to "Do this in memory of me." And, again, they did it literally, and not symbolically. They did (and continue to do) what Christ did changing bread and wine into His body and blood in a sacrificial manner. Had our Lord been speaking to them only figuratively, no one else would have been able eat and drink His promised lifegiving flesh and blood.
The Mass is a meal -- but a sacrificial meal, making eternal life available to those who believe the words of our Lord Jesus Christ, receiving His Body and Blood at the Holy Sacrifice.