Why did monotheism gain precedence over polytheism?
If you go back to the most ancient of writings in the Bible, in the Hindu scriptures, in China…you will find monotheism was first. A great deal of polytheism can be traced linguistically to just a few people in a particular time in history. One rather interesting job of this was done by Hislop in his book Two Babylons. It is available now on net (it was first published over a hundred years ago), here: http://www.biblebelievers.com/babylon/00index.htm Whether or not you agree with the aim of the book is actually irrelevant. Read the introduction and the first two or three sections — pay especial attention to the footnotes. I did some independent research some years ago to track the accuracy of his referencing and could not fault it as far as I was able to go.