In the Old Testament sacrificial system, there was a difference between the sacrifice itself and the offering of the sacrifice to God.

The Bible describes the procedure that took place on the Day of Atonement (Yom Kippur), in Leviticus 16:11-16. First, the sacrifice was made by the high priest, and then blood was taken from it (both from a bull and a goat) into the Holy of Holies (the holiest part — the inner sanctum — of the Temple, and the Tabernacle, before the Temple) and sprinkled onto the mercy seat between the two cherubim, which was above the ark of the covenant, where God was specially present (Exodus 30:6).

The second “offering” to God was separate and distinct from the sacrifice of the animals. Before God gave Moses the Law on Mount Sinai, in Egypt, before the exodus, the feast of Passover (Exodus 12:5-13), which included a sacrifice of the Passover lamb, was a simpler form of the same sort of ritual. The famous messianic passage of Isaiah 53:4-7 alludes to the Messiah being “like a lamb that is led to the slaughter, and like a sheep that before its shearers is dumb” (53:7). The New Testament continues this analogy of Jesus as a sacrificial lamb: “the lamb of God” (John 1:29, 36), “Christ, our paschal lamb, has been sacrificed” (1 Corinthians 5:7), and “the precious blood of Christ, like that of a lamb without blemish or spot” (1 Peter 1:19).

The book of Hebrews makes lengthy comparisons between Jesus the high priest of the new covenant, compared to the high priests of the old covenant entering into the Holy of Holies once a year (Hebrews 2:17; 5:5-6; 7:26-28; 8:1; 9:11-14, 24-26; 10:10). The word “offer[ing]” appears 32 times in Hebrews — first regarding the Old Testament priests (5:1, 3; 8:3; 9:6-7), then moving on to the climactic scene in heaven of Jesus offering his sacrifice to the Father:

But when Christ had offered for all time a single sacrifice for sins, he sat down at the right hand of God. … For by a single offering he has perfected for all time those who are sanctified. (Hebrews 10:12, 14)

This offering of himself as the “paschal lamb” to the Father in heaven occurred at least 43 days after his crucifixion, because Jesus spent time on the earth after his resurrection, before he ascended to heaven. Not everything was done at the time of the crucifixion (“it is finished” — John 19:30, therefore, could not have referred to this presentation in heaven) and there is a sense in which an ongoing sacrifice is supernaturally made present to us, as I have written about in these pages. The Catholic Mass is a re-presentation of the one sacrifice on the cross, not an additional sacrifice, as if he is sacrificed again.

This theme of the one sacrifice at Calvary made present to us after the crucifixion continues in the book of Revelation, where we find that Jesus is referred to as the “lamb” 28 times — far more than any other title he is given (“Alpha and Omega,” “Lord of Lords,” “King of Kings,” etc.). Moreover, he is specifically referred to as “a Lamb standing, as though it had been slain” (Revelation 5:6), “the Lamb that was slain” (13:8), and reference is made to “the blood of the Lamb” (7:14; 12:11). Note specifically that the worship in heaven is specifically directed toward Jesus, but not as the triumphant King Jesus; rather, it’s to the sacrificial lamb (Revelation 5:9, 11-12):

And they sang a new song, saying, Worthy art thou to take the scroll and to open its seals, for thou wast slain and by thy blood didst ransom men for God from every tribe and tongue and people and nation. … Then I looked, and I heard around the throne and the living creatures and the elders the voice of many angels, numbering myriads of myriads and thousands of thousands, saying with a loud voice, Worthy is the Lamb who was slain, to receive power and wealth and wisdom and might and honor and glory and blessing! (cf. 22:3: ‘The throne of God and of the Lamb shall be in it, and his servants shall worship him’)

This describes what we believe happens at Mass, where the priest and congregation take part in offering Jesus up (in the one sacrifice of the cross; not an additional sacrifice). And we partake of the Body and Blood of our “paschal lamb.”

Protestants often point out that Jesus is now triumphant in heaven and object to Catholics “always going back to the cross.” That appears to be their emphasis. Hence Protestant churches have bare crosses, as opposed to crucifixes. Yet when we see in God’s inspired word what actually occurs in heaven, we don’t find that state of affairs at all. We see the Lamb “slain” and worshiped as the slain lamb, and the passion of Christ is not “de-emphasized.” Rather, it’s still “present” and very much front and center, almost like a “living crucifix.”

The book of Revelation is usually dated at the end of the Roman emperor Domitian’s reign. He died in A.D. 96 — about 66 years after the crucifixion of Christ. Yet even then St. John saw Jesus as a slain lamb, and witnessed him being worshiped in heaven as such, too. And he continues to refer to Jesus as the “Lamb” during the time of the last days, the Second Coming, heaven after the end of the age, and even into the eternity that God allowed him to foresee (Revelation 6:15-17; 14:1, 9-11; 17:14; 19:9; 22:1-3).

If Jesus as a “slain lamb” is still a present factor in the last-written book of the Bible, describing events far into the future, then by the same token, it appears plausible and likely that the crucified Jesus is indeed present at every Mass. We imitate the worship that is described in Revelation 5:6-12 and 22:3.