Eve was deceived by Satan and the talking serpent that God put in Eden. This caused the Original Sin concept that Christianity calls a happy fault and necessary to God’s plan.
Was gaining an education and a moral sense, which basically is what gaining knowledge is, justifiable to you?
Anyone with awareness is able to understand this story as it relates to inner truth.
Anyone without awareness will only understand this story as it relates to the carnal mind or ego.
The esoteric interpretation is that the idea of original sin has nothing to do with literally eating forbidden fruit and being punished for it. These are just symbols that the carnal mind does not recognize. The "original sin" is merely the belief that the "serpent" and the "forbidden fruit" that it offers, which really represent the spinal cord / nervous system (and the forbidden fruit its sensory world), is more "real" than the original innate connection to divine will, and the belief that this world separates us from divine will, which creates a state of mind in which the ego personality takes control and the deeper mind is ignored, which in turn strengthens the belief that the outer reality is the only experience available and the belief in the ego personality as the only aspect of ourselves that is real.
There is also the symbol of satan as lighting that falls from heaven, another symbol of electricity and the nervous system, and the descent from heaven represents the indulgence of man in actions that are inharmonious with divine will as a result of the belief that the ego's illusion of "apartness" is real.
Ironically, and likely intentionally, religious dogma surrounding the idea of original sin also reinforces this idea that we are separate from God by first attacking the identity, then also planting the mental suggestion that it is the only thing worth saving. (This is also so similar to how brainwashing works that I don't believe it is a coincidence.)
The reality, of course, is that nothing can exist in opposition to divine principles, and nothing can ever be truly separate from the divine mind, or God, or infinite consciousness, or whatever terminology you prefer. Any belief otherwise is merely an illusory mental construct that we are choosing to cling on to in order to convince ourselves it's all "real".
This is not to imply the universe is some grand mistake, but rather a chosen set of limitations. An appropriate analogy is the cutting of the umbilical cord as opposed to never leaving the safety and security of the womb in order to experience what is needed.