Just curious. What is your thinking on that?
For a Christian, it is Jesus' death that saves rather than his life. In his death he paid the penalty for sin that sinners like me deserve from a perfect, just and holy God. God has to punish sin otherwise he would not be just. It is only because Jesus took the wrath and judgment I deserve that I am saved from it. Further, I am reconciled to God and have peace with him through Christ's work in his death. God sent Jesus to die for us because he loved us even when we were against him.
I do not fear the judgment that is coming by God on a sinful world because his wrath for my sin has been spent on Jesus. There is none left for me. That is why Jesus Christ is my savior. He saved me from the judgment and wrath I deserve.
Finally, I have done nothing to deserve being saved. It is only by grace, where grace is defined as God's kindness towards those that deserve his wrath. Each of us much ask ourselves how we will fare in the final judgment. Not believing it is coming will not count for much when it arrives.
That is why Good Friday (commemorating the Crucifixion) is called Good. With that act, God directly took the action necessary to repair the consequences of the Fall.
Also to point out, of all beings known, only God is worth more than the collective worth of humanity. Christ was God, and God died in the place of Man. God alone was the only single being capable of paying that high a price (and the only being in the universe with the right to take that being's own life).
I have heard what you go on to describe called the "substitionary theory." This starts with the premise that all of wicked mankind deserves punishment from wrathful God, and Jesus in effect took that whipping for us. That is a way to look at it, but not all Christians subscribe to this belief or would state it quite that way.
Roman Catholics put a great deal of emphasis on the incarnation of Christ, God became man. That puts a lot of importance on Jesus's very being and therefore his life, instead of just his death.
Orthodox Christians view the crucifixion as a rescue mission, not a punishment.
A lot of misunderstandings can result from the substitutionary theory. I once head the story of an atheist who said he could not believe in a God that was so wrathful he would kill his own son; a Christian replied that he could not believe is such a God either.