I do not read the Genesis myth as a fall from an original state of perfection into sin and death. The first couple were completely innocent and naive creatures. They were certainly capable of making a mistake but, without knowing good from evil, they lacked even the ability to sin. That ability came only with them eating of the "Tree of the Knowledge of Good and Evil". To me the story is a "coming of age story". Our mythical first couple graduated from animal status into to fully self aware human beings capable of making moral judgements. This is not an Original Sin story but rather an Original Blessing story that should be celebrated. We are not a people fallen from an original state of perfection into sin and death.
Why the expulsion from Eden? In the mythology, I believe it to be symbolic that mankind was no longer a naïve creature living in moral ignorance but had become real men and women living in a real world where there was real good and evil.
What we are is a people that is still evolving and that evolution has profoundly affected not just our bodies but our psyches as well. The world in which we evolved was a difficult and dagerous one and mere survival was of the highest priority. Selfishness became a part of who we are as a survival mechanism. This selfish instinct is no longer as necessary as in our savage past but it is still powerful. If there is an "Original Sin", this is it. Of course it is not a sin really but an innate part of our nature and it can be overcome.
In the words of John Spong: "Every living thing, plant and animal is programmed to survive. What is true of all these living things is also true of human life. The only difference is that we human beings are self-conscious, while plants and animals are not. If survival is our highest goal, self-centeredness is inevitable and thus this quality becomes a constant part of the human experience. Traditionally, the church has called this "original sin" and has explained it with the myth of the fall. That was simply wrong. Survival is a quality found in life itself. There was no fall. Self-centered, survival driven, self-conscious creatures is simply who we are. There is thus no such thing as "original sin" from which we need to be rescued by a divine invader. So much of traditional Christianity assumes this false premise."
