Sin is nothing more than separation from God. There is separation aka sin when we believe any self-limiting thought.
The snake symbolizes the subconscious mind which repeats the mantra that our ego can create a better existence by acquiring the knowledge of good and evil, and thereby exerting control over the material world. Once Eve tasted this knowledge, all of the limitations of the material world were “known” to her.
Eve immediately noticed that she was naked and she became afraid of being perceived as such in the eyes of God. Adam and Eve were no longer suitable inhabitants for the Garden of Eden because they were now identified as their egos, and the ego cannot conceive such a reality. God banished them as a natural reaction to the thoughts they were projecting – it was not a punishment.
What Eve didn’t realize was that she was always welcome back into the garden if she would only repent (return to her real Self – not identified as ego). We have this power too!