Why does it prevail in three religions that grew in three different
- You yourself referred to all three as "Abrahamic religions", so
obviously they have a common core, although each evolved over time
in its own way. That common core is the Bible, particularly the
first five books, commonly known as the Pentateuch. In these books
(although each of the faiths you mentioned has its own particular
way of translating, editing and interpreting them) the History of
Abraham (thus "Abrahamic") and his descendents, the original Jewish
people according the biblical account, are detailed, and the core
theology shared by all the Abrahamic religions is laid out. So, the
three Abrahamic religions share a great deal in terms of their
theology and world view, irrespective of time and the various
diffences in the particulars of their respective theologies.
what social context that acted as a background to this tendency?
Although, you are concerned with 'social context' it is important to
keep in mind a point that escapes many modern people - certainly
laymen, and regrettably, even some scholars: The lives of ancient
peoples were filled with 'religion' or 'superstition' or
'spiritualism' or whatever term you choose to use.
I daresay you will not find an ancient civilization or culture that
was not dominated by its priests or shamans or some similar sort of person or group - be it in Africa or the Americas or Asia or the
remote Pacific. The artifacts prove it, the documents prove it, the
myths and traditions prove it. Temporal power was bound to
religious/spiritual power - the king was most often a godhead or
descendant of one, and was often also the high priest or head of the
religion - religion, politics and society at large were inexorably
bound together. The notion of separating things into 'sociological'
as opposed to 'religious' is to a great extent fallacious when
dealing with the ancients. References and proofs of this are so
abundant that I cannot even begin to cite: think of the Ancient
Egyptian inscriptions and ruins, most notabley the Pyramids, the
Mayan ruins, the ancient structures in southeast Asia, and North
America, the Nordic myths....
So, to your question: The discussion is a long one, but the core answer is found in the biblical account of Adam and Eve and what theologians refer to as The Fall of Man or Original Sin: In Genesis 2-25, immediately after the creation of Eve, the Bible relates the following (I am translating directly from the original Hebrew text which lies before me): "And both of them, the man and his wife, were naked, but were not embarrassed (thereby)." i.e. nudity and the implied sexual relationship between "the man and his wife" were public and not a matter of shame that needed to be hidden away - quite similar indeed to the outlook held by many non-Abrahamic religions, as you mentioned in your question.
According to the biblical account, at that time God had commended Adam not to eat from the "Tree of Knowledge of Good and Evil". The Fall of Man occurred when Adam and Eve partook of the Fruit of the tree of knowledge, recounted in Genesis 3-6 "... and she took of the fruit (of the forbidden "Tree of Knowledge") and ate it, and also gave to her husband, and he (also) ate". Man (Mankind according to the Abrahamic tradition) had fallen from the grace of God by violating his commandment not to eat from the Forbidden Fruit. Adam and Eve were subsequently scolded and punished by God for their transgression, as recounted in Genesis 3-16,17 and other verses there.
However immediately after eating of the forbidden fruit, there in Genesis 3-7, we find the following very provocative verse: "And their (Adam and Eve's) eyes were opened (metaphorically speaking - the intent is that they became aware of something) and they knew that they were naked, and (so) they sowed fig leaves together and made for themselves loinclothes (to cover their nakedness)". That is, they realized that their nakedness and sexuality should be private and hidden away from view.
Therein lies the key to your answer: The "knowledge" imparted to Adam and Eve by eating of the forbidden fruit was the awareness of shame - the loss of innocence with respect to their bodies and their sexuality. This is one of the most important results of The Fall of Man according to all of the Abrahamic religions. Regarding these very early and fundamental verses of the Bible, there is little or no dispute as to their meaning and import.
Now: Regardless of their varying theologies concerning redemption, etc, the Abrahamic religions agree that since the time of the Fall of Man, mankind remains with that stain and that shame that Adam and Eve suffered after they first ate from the Forbidden Fruit, and this shame will not be removed until the time of complete redemption from Man's Original Sin - the eating of the Forbidden Fruit. Therefore, all of these religions believe that until the time of Redemption (each faith according to its own definition thereof) it is appropriate-mandatory that Man/Mankind conduct themselves as did Adam and Eve - nakedness should be covered, sexuality kept private.
As you illustrated in your question, this view is not shared by the non-Abrahamic religions, whose theologies are not based on the Biblical Account of the Fall of Man and its consequences.