Purpose of Jesus' death

This page asks why God has allowed to kill Jesus.

There are many answers to this question, but most of them have certain deficiencies. For example: the answer "Jesus was punished for our sins instead of us, so that God could satisfy His wrath, so there are no more reason to punish us." has the following deficiency: It lacks and explanation why God needs to punish somebody, why God considers OK to punish Jesus instead of us; moreover this looks as an urgent injustice to punish not that person which sinned.

Having believing Bible that God allowed Jesus to die instead of us, we nevertheless need to construct an explanation which fits our minds and does not look like a contradiction.

There is a good article on this topic: Why Did Jesus Die? (Paper for 2016 Theological Conference). This article explains various existing explanations of Jesus' death, giving pro and contras for various explanations.

Victor Porton's explanation

While reading this article, I came up with an idea (first published in my blog:

Christ’s death was to demonstrate that an altruistic person will be rewarded (as in Christ’s resurrection and power over the entire heavens given) justly, even when at first it seems that this way leads to death.

This has shown to the heavenly powers that altruism works and leads to life rather than to death as someone may expect.

And this needs a sacrifice of God himself, because it is necessary to show that even the highest level of altruism is rewarded.

Please discuss this my idea further, especially how it fits with different Bible verses.