Adam initially was in perfect stance, being spiritually alive, Jesus would walk and talk with him. The Garden of Eden was a very wonderful place with perfect climate and plenty of good food.
After a time, before any children were born, Adam did something God had specifically said was off limits, and since God is holy, he couldn't let this slide, but there is more to it than that. Eating of the tree of knowledge of good and evil apparently changed Adam, his innocence dissolved, his heart had succumbed to evil, which removed him from good standing with God.
God also planted the tree of life in the midst of the Garden, and if Adam had also eaten from it, then he would’ve gained eternal life. But, since he was in a fallen state, then he would have remained separated from God forever, so rather than let that happen, he was banished from the Garden.
There were consequences to his disobedience, which not only applied to Adam, but all his descendants throughout the millenniums. God had told Adam he would die if he ate from the tree of knowledge of good and evil, and so he died spiritually, losing his innocence. Eve was also a participant in the disobedience, and they were escorted out of the beautiful Garden of Eden, then angels guarded the entrance so they couldn't return.
The sinful state that had befallen Adam was passed to all his descendants from then to now. In other words, everybody is in a fallen state in need of redemption. This being the case, everyone is considered to be a sinner, because we are unable to live a holy life.
God had a plan to redeem mankind, knew exactly when, where, and how the plan would unfold, to every detail. Wisdom in the prophetic writings listed numerous details, written centuries prior, about the life of Jesus, and each detail happened exactly as foretold. The life of Jesus wasn't by chance, but with specific purpose.
Before living as a man, he existed in heaven. God has given him full authority over heaven and earth, from creation to eternity, subordinate only to God himself. God sent Jesus into the physical to live as one of us, to accomplish three main purposes. Jesus willingly followed his Fathers command, not only because he completely trusts our Father, but he also knew what was to be gained.
The first purpose was to reveal the character of God to the world. The second was to tell people about God's Kingdom, which he spent his whole life doing. The third was to redeem mankind, which was accomplished with his death. As a qualification to redeem mankind, Jesus had to be spiritually alive.
Since all of Adams descendants were spiritually dead, God had to perform a miracle to bring this about. The Holy Spirit caused Mary to be pregnant, therefore her son was born spiritually alive, not a descendent of Adam.
Jesus learned of his fate well ahead of time, and willingly stepped forth anyway. He allowed himself to be taken into custody, mercilessly whipped, brutally beaten, publicly mocked, and crucified. All of this was not only to pay for our sins, but also to heal us and free us from the binding power of evil.
“Then Jesus shouted, “Father, I entrust my spirit into your hands!” And with those words he breathed his last.”
Luke 23:46 NLT
“He was pierced for our rebellion, crushed for our sins. He was beaten so we could be whole. He was whipped so we could be healed.”
Isa 53:5 NLT
It's puzzling why God's solution to redeem mankind required Jesus to suffer a horrible death. We can't understand this by our own wisdom, we have to trust God's unlimited wisdom.
“Just as death came into the world through a man, now the resurrection from the dead has begun through another man. Just as everyone dies because we all belong to Adam, everyone who belongs to Christ will be given new life. But there is an order to this resurrection: Christ was raised as the first of the harvest; then all who belong to Christ will be raised when he comes back.”
1 Cor 15:21-23 NLT
At the moment Jesus died, the huge curtain in the temple ripped from top to bottom, because the New Covenant had been activated. One aspect to the Covenant, is Christians are now the temple of God, and the Holy Spirit will be with us for the rest of our lives. When we accept Jesus as our Savior and Lord, the Holy Spirit comes upon us according to his timing, likely when he sees our heart has become humble and submitted to God.
“Even as Peter was saying these things, the Holy Spirit fell upon all who were listening to the message.”
Acts 10:44 NLT
Fall and Rise of Man 2 - Born Again
Heaven 2 - Prophecy