It's very difficult to make sense of it all.
It is most especially hard to understand when Christendom makes a complete mess of the whole thing. There are so many introduced ideas that all conflict, so how can anyone get to the bottom of it...talk about confusion!
The idea of atonement in the western chuches is weird. Jesus suffers a punishment on our behalf? Where's the justice in that? The eastern chuches say he became man so that men could become divine. Where's the logical connection?
There is no logical connection in any of it. People are so busy gorging themselves on chocolate and hot cross buns that they have no idea what it's all about.
"Atonement" is literally "at-one-ment"...one action cancels out the other.
How does the sacrificing of Jesus' life "atone" for the life that Adam forfeited?
Simple. The law of God stated that equivalency was required to settle a debt or to pay for a crime. God's law was "eye for an eye, tooth for a tooth, life for a life".....so when Adam lost his perfect life by disobeying his Creator, only another equivalent life could be offered in "atonement". Since Adam's sin resulted in imperfection or defects in his genetics, (the original word for "sin" was an archery term meaning to "miss the mark") only an equivalent (perfect, sinless) life could be offered in exchange to cancel the debt and fulfill the law, thereby rescuing Adam's children, subject to sin (imperfection) through no fault on their part. This is why "the flesh is weak". The strength of our spirit is the only thing that can conquer the weakness of the flesh.
If his death made people better off, then earlier generations were unjustly treated. If it didn't, what was the point?
Time is our enemy here on earth. When we understand that the Creator and those who inhabit the spirit realm are timeless beings, not bound by earth's time limitations, we can begin to comprehend that because the first rebel was not human, that the issue is a universal one, fought on universal ground in universal time.
We are not the primary objects of this issue. The first rebel was a powerful spirit being who challenged God for sovereign rule over the earth and mankind. He claimed that God was not the right one to tell us how to live...that he would be the better choice as god and ruler. In order to settle the issue once and for all, God allowed the devil a free hand to prove himself as a god and also as a ruler over mankind, promoting independent thinking and self determination. We are living in the end result of the devil's rulership. Can we not see his stamp on everything? Can we not see the evil in the earth growing steadily as time goes on. Are we not appalled that the heinous acts of inhumanity are demonstrating evil on a scale that should not exist in this age of knowledge and civilisation?
At the end of this time period, all living beings who are endowed with free will, will have made their choices about who they accept as their god and who they will accept as ruler over them.
If you know what's going on, you can see clearly that now the world is in the same state now as it was in the days of Noah. Jesus said that just as people refused to listen to Noah's warning back then, they would do so again before he comes to end the devil's rulership once and for all. (Matt 24:36-39; Dan 2:44)
What is accomplished by God's permission of satan's rulership?
Humans get to see firsthand what happens to the world when they reject God's laws and refuse to surrender their own will to his. The abuse of free will is what got us into this mess. Doing things "our" way has never worked. We have tried every conceivable form of self rule, but none of them work for the benefit of all......why? Because power corrupts, every time. We are not designed to rule ourselves.....we are designed to be ruled by God. (Jer 10:23)
All intelligent creatures are given opportunity to make choices about whom they will obey and whom they will serve as sovereign over them....both in heaven and on earth. The outcomes for both positions is clearly stated so no one can cry foul. We are given the choice....obey God and live...disobey God and lose your life.
Legal precedents are created by allowing things to come to their natural conclusion. No one can accuse God of not allowing humans and angels enough time to see the folly of trying to do things their way. This will mean that no intelligent being will ever be able to rebel against the rightness of God's proven rulership, ever again. Precedents create the basis for all future judgment. No rebel will ever disturb the peace of others again.
Free will is retained as the wonderful gift it was meant to be, rather than the curse it became when humans and angels abused it....and God can get on with his purpose for the rest of forever unhindered.