What does Luke 22:20 mean?
As Jesus presents the third cup of wine at the Passover seder, He talks about the new covenant. This was already promised in the Old Testament (Jeremiah 31:31–34), and Jesus the means to fulfill it.The covenants of God are t promises made to certain people. Some of these involved actions which people needed to perform. In all cases, however, and in all times and places, people must have faith in God and what He has revealed to them in their place and time to be saved. Looking through Hebrews 11:7–12, we see that Noah displayed his faith by building an ark. Abraham showed His faith by being willing to offer his son. In the new covenant, we must believe that Jesus' death paid for our sins. If we admit we have sinned against God, desire to stop sinning against Him, and ask Jesus to forgive our sins—if we have faith in Jesus—He will forgive our sins and we will be reconciled to God (John 3:16–18; Romans 10:9–13; Ephesians 2:1–10).
Neither the Abrahamic nor Mosaic covenants involved taking blood from a live animal. Both required killing animals (Genesis 15:7–10; Exodus 12:3–6). When the Bible talks about Jesus' "shed blood," it's not literally speaking about body fluid. The emphasis is on His sacrificial death. Jesus says the wine is "poured out." Genesis 9:5 says that blood means life. Isaiah 53:12 says, "he poured out his soul to death."
Crucifixion doesn't typically involve massive bleeding. It was designed to induce unimaginable pain, exposure, and eventual suffocation. The beatings and scourging (John 19:1–3) caused Jesus' blood to flow freely. When the guard puts his spear into Jesus' side (John 19:34), blood and water flow out. Jesus' "blood sacrifice" refers to His death and not merely His literal blood.
Jeremiah 31:31–40 describes the new covenant. It promises the people will have the law written on their hearts. They shall all know Him. Jerusalem—all of Israel—will be restored. The new covenant is possible because Jesus died. We participate in Communion—eating bread and drinking wine (or grape juice) with fellow believers—to "proclaim the Lord's death until he comes" (1 Corinthians 11:23–26).