Alma Ch42

Sadly this is the last of the words that Alma speaks to Corianton and they focus on repenting and serving God while we are still on earth and being redeemed through the atonement. God is merciful to those who repent but others are subject to the justice of life and will answer for their sins. Only the truly penitent will be saved in the end.
The reason the talk with Corianton has gone on so long is because he has felt uneasy or worried about some of the things that were mentioned and maybe doesn't fully understand all that has been said concerning the mysteries of God. What is seems like is that he thinks that it is injustice for anyone to be consigned to endless misery, but Alma explains in the most simple way possible by referring to the very first transgression in the garden of Eden (v1-2). After Adam and Eve ate of the tree of knowledge they became like God, which means we are also kind of like God, knowing good from evil and being able to choose. Having this blessing but not the blessing of eating of the tree of life, we are not able to become fully as God, so it is a good thing we have a time to prepare to partake of that fruit so we have a chance to repent and live forever in happiness instead of misery (v3-6).
Yes it is our first parents fault that we are fallen and need repenting, but it is also their doing that we have a chance to live forever is we do repent with our agency which will fulfill the plan of happiness that was created (v7-8). Our soul cannot die, but the spiritual death means being cut off from the presence of God and we would be if it weren't for the plan of redemption which is told to us by Him through prophets and revelation during this time to prepare (v9-11).
Honestly, there is no way to reclaim us from our fallen state if we do not repent because then mercy would destroy the work of justice which would make God loose his Godhood and power (v12-14). The only way we can add in the plan of mercy to try and help mankind have a way to escape the chains of justice is for an atonement to be made by Jesus Christ to appease the demands of justice and allow God to keep his authority and be merciful like unto his nature (v15). Unfortunately, those who do not take advantage of the plan of mercy and repent will have to pay for their sins himself to satisfy the law and be punished accordingly (v16-18). Everyone fears death as a punishment which is proof that there is a law that will inflict punishment, through repentance we are allowed mercy to pay the price for that punishment (v19-22).
Now all this is still somewhat confusing to me but I know that God is still God and is merciful because of the sacrifice His son, Jesus Christ, went through to bring to pass the atonement and resurrection of the dead to be restored to the presence of God (v23). The punishment and price has been paid for by Christ so there is no longer an issue of mercy robbing justice, there is just the fact that we repent to have it take its affect on us and deliver ourselves out of endless misery (v24-26). Everyone is invited to take advantage of this gift because in the end, everyone will be restored and live forever because it has been paid for, but only a few will live in happiness with God because they are clean after repenting (v27-28). If you were or are troubled like Corianton was, deny the justice of God no more, sin no more, and let the mercy of God bring you down to humility and repentance with true conviction of heart and soul (v29-31).