In the Bible, the power of life is understood to be present in blood. This is true of animals (Gen 9.4) and of humans (Lev 17.11). No one was to eat meat that still had the blood in it (Lev 17.10-12; Deut 12.23-24) or touch a bloody dead animal (Lev 17.15,16). To kill another human being is to “shed blood,” and the blood of the victim is “on the head” of the murderer (see for example, 1 Kgs 2.31-33). The shedding of innocent blood could make the land itself cursed (Gen 4.10-12) or ritually unclean (Num 35.33-34). Because David spilled so much blood by fighting with his enemies, he was said to be unfit to build the temple (1 Chr 22.8; 28.3).

Blood was considered evidence of God-given life. Because of this, Israel's priests used blood to prepare the sacrifices they offered to God for the benefit of the people. The altar was to be made ready for sacrifices by the sprinkling of blood (Lev 1.5-11; 4.3-7; 6.24-30; 8.15), and the priests had to have blood put on them so they could become fit to come into God's presence (Exod 29.19-21; Lev 8.22-30). When the people of Israel were preparing to escape from Egypt, they were told to sprinkle blood on the outside of their doors to protect them from the Lord's angel that would pass over Egypt and kill the oldest son in each family (Exod 12). At Mount Sinai, blood was poured out to make firm the agreement (covenant) between God and the Israelite people (Exod 24.8). In the place where they worshiped God, blood continued to cleanse them and to confirm their special relationship (Lev 1).

Because of the Old Testament beliefs about blood and sacrifice, Jesus' death had certain meaning to New Testament writers like Paul. Paul describes Jesus' death on the cross as a “sacrifice,” and understood that Christ offered his blood so people could be forgiven and be made acceptable to God (Rom 3.25-26; see also Col 1.20). The writer of Hebrews says that the blood of Jesus has a more powerful purifying effect than the blood sacrifices of ancient Israel (Heb 9.20-22; 10.3-4). Christ's blood (death) makes it possible for believers to have a complete and everlasting relationship with God (Heb 10.19-22). In 1 Peter, Christ is described as the “spotless lamb,” whose blood rescues people from being slaves to sin (1 Pet 1.18,19). When Christians take part in the Lord's Supper, they are sharing in the body and blood of Jesus (1 Cor 11.23-32; John 6.53-56).