Most modern Christians believe that Jesus suffered and died in order to pay for everyone's sins. By sacrificing himself, he brought about the atonement that allowed God to forgive us and offer us salvation.
But many people wonder why God didn't just forgive everyone outright, without requiring a sacrifice first. There are several possible explanations for why a sacrifice was necessary. Known as Atonement Theories, they may be briefly described as follows:
In Mark 10:45 Jesus says that he came to give his life "as a ransom for many." The idea that he died in order to pay a ransom is the basis for the Ransom Theory. This is one of the oldest atonement theories, and during the first thousand years of Christianity, it was the most common explanation for why Jesus had to suffer and die.
The early Christian scholar Origen gave one of the first detailed descriptions of this theory. He said that the disobedience of Adam and Eve caused God to abandon humankind to the Devil, who then exerted his power over us. Later, when God decided to reconcile with us, he agreed to pay Satan a ransom for our release. The agreed-upon payment was Jesus' death on the cross. After the crucifixion, Satan kept his part of the bargain by releasing us from his power. But then God pulled a trick on him by resurrecting Jesus.
Some later writers argued that God's trickery was justified because the Devil himself is so dishonest. Others said that Satan should have known not to ask for Jesus' death in the first place, and therefore got just what he deserved.
The Ransom Theory is also called the Bargain Theory and the Classical Theory. It was the primary atonement theory for more than a thousand years, from the first century to the eleventh century, and is still accepted by some Christians.
The eleventh-century scholar Saint Anselm didn't like the Ransom Theory. He believed that an outlaw like the Devil had no right to exert power over humankind, and therefore God didn't need to pay him anything for our release.
To replace the Ransom Theory, Anselm put forward another explanation known as the Satisfaction Theory (or Debt Theory). According to this theory, humankind owes a debt to God because we dishonored him through our disobedience and sin. But his pride, as well as the need for universal justice, prevents him from simply forgiving us. To resolve the matter, Jesus volunteered to pay our debt for us by suffering and dying on the cross. God accepted this act of love as a full atonement, and thus satisfied, he then forgave us and offered us salvation.
Some people still wonder why God didn't just forgive us outright. Another criticism of this theory is that it puts Jesus in the role of a sacrificial lamb. In ancient times lambs and other animals were often sacrificed to pagan gods as a way to appease them. It was thought that the death of an animal could serve as a substitute payment for a person's sins. Similarly, in the Satisfaction Theory, the suffering and death of Jesus serves as a substitute payment for humankind's sins.
According to this theory, Jesus tried to help us obtain salvation by giving us a perfect moral example of how to live. He hoped that his teachings and his example would inspire us to lift ourselves out of sin and enter into true communion with God.
This theory, which is also called the Moral Influence Theory, is usually attributed to the medieval scholar Peter Abelard. Many Christians have found it attractive and helpful. But some people wonder how it explains the crucifixion, since Jesus could have given us his teachings, and also provided a perfect moral example, without dying on the cross. One possible answer is that his death, though not strictly necessary, helped to draw attention to his life and therefore made his mission more effective.
Unfortunately, many people continue to ignore the example that Jesus set, and still commit immoral acts. Thus, if the purpose of his mission was to inspire everyone to live without sin, so far it hasn't been fully successful.
The basic idea of this theory is that Jesus suffered and died to take upon himself the punishment that we ourselves deserve. Although God wasn't willing to forgive us outright, he was willing to accept the punishment of Jesus as a substitute for our own punishment. Thus, in this theory Jesus takes the role of an innocent scapegoat who is punished for the sins of others.
On one occasion God punished humankind by sending a flood that killed everyone on the earth except a few people on Noah's boat. But according to the Penal-Substitution theory, when humankind later needed to be punished again, God allowed Jesus to take the punishment for us.
Some of the underlying assumptions of this theory can be found in the letters of Saint Paul. The Protestant Reformers of the sixteenth century took those assumptions and developed them into the modern form of the theory. In some ways it resembles the Satisfaction Theory, since Jesus' act of taking our punishment for us is basically equivalent to paying our debt for us.
The Penal-Substitution Theory is accepted by many modern Protestants. Most of them also believe that Jesus' sacrifice brought the possibility of forgiveness to everyone, including people who have lived since the crucifixion and people who will be born in the future. This is known as universal atonement. But some Christians believe that Jesus died only for the "elect", a small minority who are predestined to be saved. This is called definite (or limited) atonement.
According to this theory, God acts as a governor (or overseer) of all life on the earth. But he became very displeased with the way people were behaving, and he wanted to show us that we deserve severe punishment. To demonstrate just how severe, he sent Jesus to suffer and die.
Thus, the crucifixion was meant to be a demonstration of the punishment that we all deserve. By giving us this demonstration, God hoped that we would realize the seriousness of our sins and reform ourselves. He could have actually punished us, and would have been justified in doing so, but decided to merely give us a warning, and let us have another chance.
One problem with this theory is the fact that many people have lived and died without ever hearing about Jesus or the crucifixion, and therefore were never aware of God's warning. And even now, many people who are aware of it appear to disregard it.
In 1931 Gustaf Aulen published the book Christus Victor, in which he argued that Jesus came to earth to defeat the evil forces that had gained control over us. To win our salvation, Jesus needed to overcome both Satan and death. The name Christus Victor, which means "Christ the Victor", refers to his successful accomplishment of this task.
In some ways this theory is similar to the Ransom Theory, for it assumes that humankind had come under the control of the Devil after the sins of Adam and Eve caused God to abandon us. But in this theory, instead of God paying Satan a ransom for our release, Jesus freed us by directly defeating the Evil One. And his resurrection proved that death can also be conquered.
In his book Aulen argues that this was the original belief of the earliest Christians. It is also the basic belief of many modern Eastern Orthodox Christians, and in recent years it has become popular among some evangelical Christians.
The starting point for all of these theories is the alienation from God brought about by humankind's sins. This alienation is what allowed the Devil to gain influence over us and lead us into even greater sin.
In some theories the first step in solving the problem is to free humankind from the Devil's influence. In other theories that step can be skipped, because Satan will automatically be pushed aside if we reconcile with God.
One solution would be for everyone to reform themselves and start living in accordance with God's wishes. But there is apparently very little chance that this will happen. Therefore any reconciliation between God and humankind requires a divine action. The simplest action would be for God to simply forgive everyone unconditionally. But he wasn't willing to do this, and so another way to bring about the reconciliation had to be found.