The Tree of Knowledge and its fruit, the Forbidden Fruit, are taken literally by some Christian sects as real elements of the once-existent Garden of Eden. In the Bible, Eve eats of the fruit after being tempted by Satan and then urges her own sin upon the hapless Adam.
After eating the fruit, they are both suddenly 'aware of their nakedness and become ashamed. As punishment for eating of the fruit God forbade, they are exiled from Eden.
This story can be read symbolically to imply that it is man's 'intellect that expels him from the simple, natural world that belongs to the animal kingdom and the rest of creation i.e. Eden.
The symbol of the Tree of Knowledge has become meaningful to several occult and esoteric societies - no longer as an object of man's downfall but rather as an object to be desired and striven for. Why should God deny mankind Knowledge?
In this capacity. Satan, or more often called by these groups Lucifer, or light bringer'. is the revered bearer of knowledge -- hero instead of opponent. They reason that if man had the knowledge God would deny them, they might become Gods themselves.
Immortality has also been associated at times with the 'forbidden fruit”.