Mark 14:22-25 NLT
As they were eating, Jesus took some bread and blessed it. Then he broke it in pieces and gave it to the disciples, saying, “Take it, for this is my body.” And he took a cup of wine and gave thanks to God for it. He gave it to them, and they all drank from it. And he said to them, “This is my blood, which confirms the covenant between God and his people. It is poured out as a sacrifice for many.* I tell you the truth, I will not drink wine again until the day I drink it new in the Kingdom of God.” *emphasis added
Reflection . . .
In this passage Jesus was eating with his disciples and pointing them to the fact that He was the one who would fulfill the New Covenant God had planned for his people.
They had been waiting hundreds of years, and now Jesus is saying that the cup which represents his blood would be poured out as a sacrifice, and that his death, the sheding of his blood would be the foundation of this New Covenant. Why blood? Why death? Because without the shedding of blood there is no forgiveness of sin and Christ is the one who bore our sin and shame in our place.
Hebrews 9:11-28 for the full passage, which explains . . .
Hebrews 9:11-12 NLT
. . . So Christ has now become the High Priest over all the good things that have come. He has entered that greater, more perfect Tabernacle in heaven, which was not made by human hands and is not part of this created world. With his own blood—not the blood of goats and calves—he entered the Most Holy Place once for all time and secured our redemption forever.