Alma Chapter 42

42:1 - "...And now, my son, I perceive there is somewhat more which doth worry your mind, which ye cannot understand—which is concerning the justice of God in the punishment of the sinner; for ye do try to suppose that it is injustice that the sinner should be consigned to a state of misery..."
It may seem somewhat unjust that the sinner should be consigned to a state of misery - wouldn't it be better to have hope in repentance and faith?
Yes, we should have hope in faith and repentance, but the point of the misery is to lead us back unto Christ.
Plus, the misery really helps us to appreciate the joy of being in the presence of the Lord.


42:2-5 - "...Now, we see that the man had become as God, knowing good and evil; and lest he should put forth his hand, and take also of the tree of life, and eat and live forever, the Lord God placed cherubim and the flaming sword, that he should not partake of the fruit..."
If Adam had taken of the tree of life, he would have lived forever.  This appears to be the same tree of life that is in Lehi's dream - which may give more insight into why Cherubim and a Flaming Sword was placed to guard the tree of life.
Many people in Lehi's dream partook of the fruit of the tree of life, but still needed to hold fast, because some of them fell away after partaking.  If Adam did not learn more, it seems that he would have lived forever in a state that would have been similar to falling away after partaking.
God in His mercy gave Adam the opportunity to learn and grow and progress and approach closer though the proper means.  We also have this opportunity, and must follow the commandments.


42:13 - "...Therefore, according to justice, the plan of redemption could not be brought about, only on conditions of repentance of men in this probationary state..."
We do have help from the Lord.  He suffered everything for us, and we can have that cover us completely.  Our job is to have faith in Him and repent of our sins...continually trying to get closer to Him.
As we act in faith, we will see those blessings, including forgiveness and the companionship of the Holy Ghost.