In fact, the law requires that nearly everything be cleansed with blood, and without the shedding of blood there is no forgiveness. It was necessary, then, for the copies of the heavenly things to be purified with these sacrifices, but the heavenly things themselves with better sacrifices than these. For Christ did not enter a man-made sanctuary that was only a copy of the true one; he entered heaven itself, now to appear for us in God's presence. Nor did he enter heaven to offer himself again and again, the way the high priest enters the Most Holy Place every year with blood that is not his own. Then Christ would have had to suffer many times since the creation of the world. But now he has appeared once for all at the end of the ages to do away with sin by the sacrifice of himself (9:22-26, NIV).
Why does God insist on "redemptive violence"? Brown and Parker write:
The central image of Christ on the cross as the savior of the world communicates the message that suffering is redemptive. […] The message is complicated further by the theology that says Christ suffered in obedience to his Father’s will. Divine child abuse is paraded as salvific and the child who suffers “without even raising a voice” is lauded as the hope of the world (Joanne Carlson Brown and Rebecca Parker, "For God So Loved the World?", in Christianity, Patriarchy, and Abuse, p. 2).
What is it about suffering and death that erases sin in God's mind? It seems barbaric and sadistic. Primitive religions all over the world offered (and some still do) blood sacrifices to appease the wrath of their god(s). It seems that man felt that in order to win the favor of his god(s), he needed to offer something of value to the god(s). What is more valuable than a life? Blood was thought to be the life principle in the body and thus when it was shed, the life was poured out. Leviticus 17:11 states: For the life of a creature is in the blood, and I have given it to you to make atonement for yourselves on the altar; it is the blood that makes atonement for one's life.
Commenting on this passage, Erhard Gerstenberger writes:
This blood gift to Yahweh actually cannot be illuminated logically, for prehistoric notions of faith are resonating in this rite. As is the case among other peoples, blood is considered to be a magical substance efficacious in and of itself. Hence with blood one can expurgate the powers of death and eliminate the stain of sin (cf. Ex. 4:25; 12:17ff., 22f.).
...Blood is thus the preeminent substance of life. This life force can redeem a life given over to death, and for that reason can also eliminate defilement and reestablish sundered fellowship. Both the author of the sacrifical laws and their audience seem to have taken as their point of departure the legal principle "a life for a life" (Ex. 21:23; Lev. 24:18-20), and to have appropriated without excessive reflection these ancient magical notions concerning the efficacy of blood. Subsequent Jewish and especially Christian theology then developed a broad atonement faith perspective associated with blood symbolism [e.g., 1 John 1:7--"the blood of Jesus Christ cleanses from all sin"] (Leviticus: A Commentary, pp. 59-60).
All of this blood and gore is repulsive and offensive to modern man. As Frank James states:
And there is, indeed, an outrageous aspect to the atonement because it revolves around such disquieting concepts as death, blood sacrifice, guilt, sin, wrath and propitiation. With such notions in view, the thoughtful Christian might ask: Why must God employ such distasteful means to effect salvation? (The Glory of the Atonement, pp. 15-16.)
In addition, the atonement perpetuates the idea that violence can accomplish good. Religion and violence have been joined at the hip since the beginning (see Hector Avalos, Fighting Words: Origins of Religious Violence)and it continues today.
If someone wishes to retain belief in Christianity and yet deny there is redemptive violence, then one is in for a difficult task. As Hans Boersma writes:
Only by radically limiting Christ’s redemptive role to his life (so that his life becomes an example to us) or by absolutely dissociating God from any role in the cross (turning the crucifixion into a solely human act) can we somehow avoid dealing with the difficulty of divine violence (Violence, Hospitality, and the Cross, p. 41).
If one finds the concept of redemptive violence to be troubling, then one will be forced to reject Christianity. Garry Williams states it this way:
Others try to rescue a re-invented theology, but I have to say I am with the rejectionists. If purposed redemptive suffering is an insurmountable problem, then Christianity must go ("Justice, Law, and Guilt"– EA Symposium on Penal Substitution).