I believe it is an abstract truth that death is not required for sins to be forgiven.  Death became a requirement when God so stipulated it.  From God’s perspective this may accomplish any number of things, about which in the absence of comment form him we may speculate.  Psychologically, perhaps sacrificing a lamb satisfies our own sense of justice, or satisfies our sense that we should somehow have to pay something, if only a token, for what we’ve done.  Or perhaps the shedding of blood impacts us in a way that makes corresponding events more grave and memorable.

What kind of sacrifice was it for God to offer his own son—knowing that this would neatly bring about everything he was working for, and that he could resurrect him to any kind of existance or station that would please him?  What is death for Christians, we who believe that our souls are immortal and that our life will continue into eternity in intimate relationship with God?  What does it mean to say that a grain of wheat dies, when it sprouts and produces many times its number in grains of wheat?

If I want to conclude a legal agreement, I am required to sign the contract.  "Agreement," abstractly, does not require a "signature."  But socially, important agreements do in fact require signatures—by stipulation, by convention.

One of my pet peeves are theologians who separate biblical rituals from the "real" or "spiritual" activity they represent, then conclude that Christians need not be obedient in following the prescribed rituals.  I see our relationship with God as covenantal—and I accept the stipulations and conventions as laid down by Christ and his apostles.  In the case of my relationship with God, I recognize that Christ died for me (he called it his blood of the new covenant, calling to my mind the blood of the heifer Moses divided between the altar to YHWH and the mixture sprinkled on the people).  I don’t see this as (abstractly) an abandonment of Jesus on God’s part, any more than I would consider myself abandoned by God should I myself be martyred.