Despite the levels at which this has sunk, let me try.
DT, my post was clearly not meant to be taken seriously (I hoped). But since you picked it up and with the fresh insights that come from the contact of wet trout skin sliding past mine, let me posit this thesis:
Religion is to knowledge of God what romance is to love (art to beauty, maybe?). Different people at different times and different places, have fallen in love. What they do about it, to conquer the love of the object of their feeling, varies a lot from what goes around in their environment. From clubbing them in the head and dragging them by their hair, to offers of grasshoppers, to chocolate, to Rolls Royces, to poem and songs, to suicide. What they have to offer to explain their love is nothing, other than their personal experience of it.
To someone who has never been in love, the notion is just alien and romance is silly and illogical. And when they eventually fall in love, the whole thing makes sense.
Likewise, people have felt the presence of God. Their expression of that experience and how they share it with other people who have had the same experience, varies with whatever is around them. Certain common themes arise, just like diffiicult to acquire presents in romance, but the details vary enormously with location and time.
To the person who has experienced God, faith and religion make no sense.
So religion varies because it is a human creation, a response to a feeling and an experience. Tradition guides it and so we see some things get carried in history and accross space sharing and sometimes outlasting novelties. The environment shapes it and so we see variation.
The underlying experience of the divine transcends both regional variation and traditions and that is why we see the same common themes throughout the whole range.
Your analogy to government is just perfect. With notable exceptions, they all share some common values: management of the common good, protection of the needy, etc. How those values are carried out in particular governments, vary a lot with the history and circumsances of that nation.