This isn't a Christian view. Judaism and Islam believe in the validity of the Old Testament, as well; their versions just differ from the Christian Bible. Also, the Fall of Man a philosophical and literary topic as much as it is a religious one.
The short and sweet version of this part of the Bible is this:
Adam and Eve's failure to follow God's one and only command stripped them from the Innocence that God gave to them. For example, immediately after eating the Fruit, Adam and Eve realized the shame of being naked, of which they were innocent beforehand. Having gained Experience of the world, they were now to face the world without his direct guidance and protection. It set the stage for all of mankind: Adam and Eve's descendants were (and are) all destined to Experience one day, putting their lives from God's hands into their own. Although God is never absent, he is allowing us to control our own actions. It also set the stage for Heaven: before eating the fruit, Adam and Eve were immortal and enjoyed God's full blessings on Earth. After eating the fruit, Adam and Eve (and all of mankind) were instead judged based on their ability to choose their actions whether or not they shall enjoy God's full blessings in Heaven when they died.
By the way, I'm not a Christian. I just understand the value of being well-read.