I have always wondered about the need for Jesus to be crucified. I have always heard that it was because of original sin. My question is if God is indeed God and presumably all powerful, why did He not simply forgive Adam and his wife? Was it beyond His scope to do so? Was the sin that bad?
Here's the LDS perspective, muslimah. We believe (unlike other Christians) that we existed in spirit form prior to being born to our earthly parents and lived for an immeasurable length of time (probably billions of years) in the presence of God. We believe He presented us with a plan and allowed us to choose whether or not to participate. The plan would involve the experience of mortality. We would each receive a physical body and spend a period of time here on earth. While here, we would learn to discern between good and evil. We would be provided with guidelines and directives from His chosen prophets, but ultimately we would be required to walk in faith.
Now, there was a "catch," although it was fully explained to us, so I don't suppose "catch" is the right word to use, after all. We were told that in order to return to God's presence, we would have to be as innocent and clean when we died as we were when we left him to go to earth. If we were able to live perfectly, never
ever sinning, we would have the benefit of all of the knowledge we had gained by the experience and would be rewarded beyond our wildest dreams when we returned. If, however, were to sin along the way, we would be forbidden to ever return to Him again. God has what you might call a "zero tolerance" policy towards sin, and even one, small sin would spoil the required perfect performance.
It was then that the pre-mortal Jesus Christ, the only one of His spirit children to be as perfect in every way as He was, stepped forward and agreed to help the rest of us out. He knew that He could lead a completely sinless life, but that we couldn't. He loved all of us as much as our Father in Heaven did, and He wanted us to not only be able to experience mortality but to return to God's presence. He therefore offered to pay the price to redeem each and every one of us who would sincerely repent whenever we fell short, and who would have faith that He would keep this promise and guarantee that we would not be eternally lost.
If you're still reading... God did not simply forgive Adam and Eve because to do so would be to disregard His own rules. He had warned them of the consequences for disobedience and can always be trusted to follow through with anything He says He will do. It was not beyond His scope to simply forgive them, but to do so would have gone against His "zero tolerance" policy. The sin, per se, wasn't all that bad. As a matter of fact, they really didn't "sin" at all, at least not by eating the forbidden fruit. They didn't even understand the difference between right and wrong before they ate it. After they ate it, though, they became accountable for their misdeeds, which is where Jesus Christ's sacrifice came into play. Since He was perfect, He was able to pay the price where they couldn't, thus satisfying both the demands of mercy and the demands of justice.
God set up the universe with consistent rules; one of them was and is that the punishment for sin is death. Thus, forgiveness is only possible when someone else pays the price. Christians believe that Christ did so for us. 
