The original sin: The woman you put here with me—she gave me some fruit from the tree, and I ate it. Genesis 3:12
Original sin is a very old explanation for the theory of evil in the world, men are sinners due to an ancestral sin committed by a man and a woman who gave rise to all humanity in a place called Eden. From philosophy, or from ethics, there is no explanation for the insistent inclination of men to error and destruction, that is why we are only left with myths to try to approach the problem. The entire Christian religion from Adam to Jesus is developed on the problem of sin in humanity, the same Christian religion concludes with the resolution of this problem in the book of Revelation.
The book of Genesis begins by telling us that man was created in a state of innocence: "Adam and his wife were both naked, and they felt no shame" Genesis 2:25; and placed in a garden where the tree of life and the tree of discernment grew: "In the middle of the garden were the tree of life and the tree of the knowledge of good and evil" Genesis 2:9.
The fact that the tree of life was in Eden means that man enjoyed immortality when he was created, and as a consequence of the growth of sin in humanity, man lost years of life: "Then the LORD said, ´My Spirit will not contend with humans forever, for they are mortal; their days will be a hundred and twenty years" Genesis 6:3.
The Bible in this sense explains that the immortality or longevity of man is a gift from God: "Knowing you is perfect righteousness. Recognizing your power is where immortality begins" Wisdom 15:3.
The Bible after the creation of man and the Garden of Eden continues to explain that the woman, tempted by an animal, offered the man the fruit of the tree of discernment, and as a result of eating the fruit, both the man and the woman acquired discernment, and they were punished by God:
"Then the man and his wife heard the sound of the LORD God as he was walking in the garden in the cool of the day, and they hid from the LORD God among the trees of the garden But the LORD God called to the man, ´Where are you?´ He answered, ´I heard you in the garden, and I was afraid because I was naked; so I hid.´ And he said, ´Who told you that you were naked? Have you eaten from the tree that I commanded you not to eat from? The man said, ´The woman you put here with me—she gave me some fruit from the tree, and I ate it´" Genesis 3:8-12.
After this, the Bible tells us that Adam and Eve were expelled from Eden, and evil through their offspring spread throughout the earth.