What is the spiritual significance of blood?
  What is the significance of Jesus' blood to us?

First, two definitions:

Life, death, substitutes and blood

To understand the spiritual significance of blood, it is first important to understand the historical significance of blood in two areas: the passover and the sacrificial system.

The passover occurred during the dramatic event when God brought the Israelites out of Egypt. They had become enslaved in Egypt, and had grown to be a nation there. God demonstrated his power to the Egyptian rulers in a series of plagues on the land culminating in the death of the firstborn children of all the Egyptians (Ex 12).

However, the Israelites were protected from this plague. They had been instructed to kill a lamb. They were to roast the meat for a meal, and to mark the blood of the animal onto the doorframe of the house. That evening, a destroyer from God went through the whole land and entered every house that was not marked with blood around the door. Inside every house, he killed the firstborn son. However, he did not enter the marked houses, because a death had already occurred there.

The lamb that supplied the blood in the Israelite houses died in substitution for the firstborn son. It prevented a human death, which is the final breaking of human relationship.

God also instituted a system of animal sacrifices with the Israelite people (Lev 4, Ex 29). Sacrifices were to be made for sin, and for consecration. The person for whom the sacrifice was being made was to lay their hand on the head of the animal, and then it was to be killed. This signified that the animal was to die in substitution for the person. The animal's blood was marked onto the altar of sacrifice, or sprinkled on the object being consecrated.

The sacrificial animal that supplied the blood died in substitution for the sinner. It prevented death that comes from sin. The most significant death is spiritual death, which is breaking of relationship with God. However, since God is justified in taking our physical life due to our sin, the animal's death also prevented a human death.

These two events taught the Israelites about life and death, sin and righteousness. Relationship only happens in life; death brings separation. Sin brings death because that is its consequence. After a sin, a return to a state of righteousness can only come to an individual if instead, some other innocent (sinless) being dies to take that consequence.

In the case of these animal sacrifices, even though animals have no sin, animals are not a direct substitute for a person. This can be seen in that the value assigned to them is less than that of a person, animals are not described as spiritual beings, they are not described as responsible to make choices between righteousness and sin, and in that animals could only substitute for unintentional sin. This is why animals were never a final solution to the problem of sin.

The Passover and the sacrificial system are called "types of Christ" because they foreshadowed Christ and were fulfilled in him. Jesus was killed during the Passover celebration, and in 1Cor 5:7, he is called our Passover lamb. In John 1:29, John the Baptist called Jesus the lamb of God who would take away the sin of the world. Many, many other places also connect Jesus as a sacrifice for us, fulfilling the sacrificial system. Jesus is both our Passover lamb and our sinless sacrificial lamb.

Since Jesus fulfilled these events, his blood is significant in the manner of the blood of the sacrificial animals. But since Jesus is also God, everything about him is significantly more valuable than the people for which he died. This is evident in that Jesus is in two ways a spiritual being (both as being God and being human), Jesus was able to substitute himself for any number of humans, Jesus took on responsibility for the righteousness of the world, and in that Jesus' death covers even intentional sin. Therefore, Jesus' solution is permanent.

However, when Jesus died his blood simply ran down right there. Also, his blood was never brought to the Jerusalem temple to mark anything for consecration. Jesus did not die to take part in earthly sacrificial ritual. He died to eliminate earthly ritual by solving the problem in the spiritual realm where the problem originated.

The meaning of blood

In the passover, the blood on the door posts was an indicator. The destroyer did not pass over the painted houses because of the blood color. It passed over because the blood on the house was an evidence of a death.

At a sacrifice of consecration, the temple implements were sprinkled with blood as an indicator. The items did not become holy because of the red color. They were considered holy because the blood was evidence of the substitutionary death of one that was innocent of sin.

When Jesus was growing up, I am sure he accidentally experienced a scraped knee and he bled. We don't know about that blood because it only indicated an incidental injury. However when he bled out on the cross, his blood indicated his death. At a death, blood is the evidence of that death.

Note that on the cross, Jesus experienced spiritual death as well as physical. His relationship with God was broken for a time ("My God, my God, why have you forsaken me?" Matt 27:46). And then his body died.

We are saved by the blood of Christ, not because his blood cells saved us. We are saved by the substitutionary death of Christ, of which his blood stands as evidence.

However, the blood of animals and the blood of Jesus also hold different meanings. The blood of the animal was real, physical evidence of a death that had immediately occurred in a ritual setting. Initially the blood of Jesus was real, physical evidence of his physical death that occurred in a punitive setting (John 20:24). Afterwards, Jesus' blood was historical evidence of his death: both the physical death and the spiritual death. Jesus' blood is a symbol of his death.

Restored Relationship

The most important part of life is our relationships. Evidence for this is the despondency we feel when we are lonely, and the universal social nature of humans. In relation to this, the most significant aspect of death is is that it cuts off relationships.

Unfortunately, a natural consequence of our selfish native value systems is broken relationships. Social training can moderate this effect between humans. However, social facade does not help our relationship with God. The unavoidable consequence of our rebellious value system - our sin - is spiritual and relationship death towards God.

In the Jewish Old Covenant spiritual system, there were sacrifices for individual sin. There was also a special annual ritual where the high priest would go behind a curtain to enter the most holy place in the tabernacle with the blood of an animal to atone for the sins of the people. This tabernacle holiest place represented the dwelling place of God. Like the sacrifices for sin, this earthly ritual had to be repeated indefinitely by human priests.

Jesus, however, entered the actual holy place of God's heavenly residence as our high priest (Heb 9). He performed this act for the last time in the place that the earthly ritual only represented. And he entered there with his blood.

Jesus certainly did not need blood to enter there for himself - he was just going home! But as a priest to God for us, in fulfillment of the ritual, he did need blood. God is a spirit, so he does not live in a physical place (Heb 9:11). Therefore, Jesus didn't bring physical blood to a spiritual place as evidence. Jesus did go into God's holy presence with evidence of his substitutionary death for us. The word "blood" is simply the word used for the evidence of that death.

The Old Testament high priestly ritual was teaching and a forward reminder of how God would solve the sin problem. Jesus came and permanently fulfilled this ritual, taking away the relationship consequence of sin between God and us. As an earthly indication of this, Mark 15:38 says that when Jesus died, the curtain of the temple was torn open (in a way that no human could have done). This was the curtain guarding that most holy place in the temple. The curtain had been a continual indicator that God and man were separated from each other by sin. Jesus permanently opened access to God and obsoleted the old high priestly ritual.

Heb 9 & 10 contrasts the old and new covenant. The first one had an earthly high priest. In this last one, Jesus God is high priest. The old covenant had external, written laws that needed external enforcement. In the new covenant, Heb 10:16 says God will make the laws internal to his people by writing them on their hearts and minds. This is the work of the Holy Spirit to transform us as we adopt God's value system as our own. We can have relationship through these common values.

The blood evidence of Jesus' death is also available for us to use (Heb 10:19). By it we also are able to enter God's very presence. By having adopted his value system, we have a basis to have relationship with him. As we spend time with him, that relationship can grow.

Conclusion

Jesus fulfilled the passover and sacrificial rituals by providing himself as the final substitutionary death for sin. His blood was evidence of this death so that the problem could be permanently solved in the spiritual realm. We are purified so that we are no longer held responsible by God for the relationship consequences of our sin.

Jesus returned to God as our high priest. He presented his blood as evidence of his substitutionary death. By this he finished the task of atoning for the sin of his people. God accepted the blood and opened access to himself for us.

Jesus' blood is spiritually significant to us as an intrinsic symbol of His death that brought us life.