Most of us were taught in school that the ancient Egyptians were polytheistic, with a god for just about everything.  A god of air, a god of water, a god of parties, etc.  Some scholars now believe that is not true.
    The confusion comes from the interpretation, or misinterpretation, or the word neter as god.  Many scholars now say it would be more accurate to interpret neter as "an aspect of God", or "a view of God".  The Egyptians recognized that there was only one God, but that God was so incredible and complex that the only way a simple human could get any understanding of him at all was to just look at small parts of God, so they gave those parts names.  That doesn't mean they believed that Anubis, Isis, Atum, Seth, Ra, etc. were separate beings competing with each other to be head god, but rather, they were symbolic representations of certain aspects of the one God.  I think that is probably true of the Romans, Mayans, Greeks and some other ancient civilizations that we think were polytheistic.