the covenant: In God’s covenant with Israel, the blood of sheep or goats was shed and put on the doorposts at Passover (Exodus 12:5, 13; 24:8). They put it on the "the sides and tops of the doorframes" (Exodus 12:7). Jesus, the sinless Lamb of God, created a new covenant with his blood (see Jeremiah 31:31). The covenant represents God's self-initiated promise to bring salvation to humanity, fulfilling the promise to the patriarch Abraham (see Genesis 12; Galatians 3:15–29; 4:12–31).
for many for the forgiveness of sins: Jesus shed his blood as a sacrifice to forgive sins (see Jeremiah 31:31–34; Mark 14:24). Some think many means only God's chosen people, while others believe it means "all" (compare Matthew 20:28).