The Abrahamic religions of Judaism, Christianity, and Islam all recount the legend of Adam and Eve in the Garden of Eden found in the Hebrew Bible, who are not aware that they are naked until they eat the fruit of the Tree of Knowledge of Good and Evil.
After this, they feel ashamed and try to cover themselves with fig leaves.[1][2] Each of these religions have their own unique understanding of what is meant to be taught with the recounting of the story of Adam and Eve and the use of nudity in the Hebrew Bible.
In Christianity, nudity is associated with original sin, an integral aspect to their doctrine of redemption and salvation. In Islam, it is to show that women and men should be covered in clothing, for nudity has the stigma of shame attached to it.
[3] In Judaism, nudity in and of itself is not sinful, being that it is a natural part of God’s divine creation. And, many of the references to nudity or “nakedness” in the Hebrew Bible is understood as a polite euphemism for intimate behavior.
[4] For example, in the legend of Noah we experience the hesitancy of two of Noah’s sons when they have to cover their father’s nakedness, averting their eyes, after Noah’s youngest son “saw his father’s nakedness and told his two brothers outside” what he had done to his father.[5][6]
http://en.wikipedia.org/wiki/Nudity_in_religion