Well…imagine this…(imagine-bcos NO ONE knows :))
Once upon a time there were people living on this planet earth with no differences like religion, caste, creed or language. As far as language was concerned, it is possible that different languages might have emerged from a single one. Just observe that the same language is being spoken in different ways at different places. May be some research in future may show that all languages had originated from the same source. However, one fact was that lot of ancient Indian knowledge were passed through oral means(i.e. not written). On alternative thinking, we can observe that our ancestors were having super brains to keep a lot of stuff in their memory and only when their memory started to fade (starting of degeneration), did they attempt to start putting down the knowledge in writing. People were not cunning but brilliant enough only to live their lives peacefully doing their own duties, and peacefully coexisting with each other in the society. No one was either superior or inferior. The works in the society could have been shared among them as per the expertise or the individual’s capacity – both mental and physical. Now, this is possible in a very small group where the numbers of inhabitants are small. With the increase in population and the expansion of settlements for living and the search for new habitat, it could have led to movement of people among different places. With the decrease in the mental capacity and the increase in population alongwith emigration and immigration of unknown people, the works in the society might have been performed by people with different capabilities resulting in mediocre performance. Well….now let’s come to reality…since it was the case of human society, the basic nature of humans being selfish & greedy, someone could have sprang from within the society who was selfish and who wanted to control the society. As everyone was blissful in his own world, no one was equipped to deal with the sudden advent of some person’s cunningness to control them. Probably “Divide and Rule” started then. Misinterpretation of the rules governing the society by the persons in authority to rule over the masses could have then begun. Corruption corrupts. Thus started the ruin of the human civilization. Then we see the arrival of many seers/prophets to preach goodness or righteousness in societies at different places. It is a fact that some of the (teachings of) seers/prophets were attracted by lots of followers and these “groups” of followers came to be known as “religions”.
A discussion on the definition of religion is also given in the link below:
Well…now what do we call the group of persons who are not followers of any of these religions. i.e. the group of people who exist since times immemorial and who remained as they were without embracing any religion as mentioned above in particular. Well, here in the Indian subcontinent they are being called as ‘Hindus” by other people. A term used, to call the inhabitants of the Indus valley. It is no doubt good for a common man that atleast a unifying factor for a country to have happened as “India”, where diverse facets of life is the key. As easily adaptable as they are, now these group of people also call themselves as “Hindus”, because the whole world calls them so. In India, one can observe there are different sets of people in this group of “Hindus” who are believers of one god, believers of several gods, worship whomsoever they feel so, people who are bashers of believers or worshippers, some are vegetarians, some are non vegetarians, etc. Some of them live by or try to live by following the ancient Indian scriptures, some practice things which others do, but most of them practice what their ancestors did. So, a “Hindu” is generally free to do whatever he wants to do according to his own conscience. People of other religions have a code to follow in each and every walk of their life, as codified by their seers/prophets. Only the interpretation of the code differs.