In Hebrew religious texts there are several different ways to refer to God (capital G). Some of these words, such as Elohim or Adonai are plural forms although it is clear that Judaism is monotheistic.
Why do some languages associated with monotheistic religions use a plural form? Do such languages use a plural form to refer to a god (lower case)? Do these words even have a singular form? Is this for the same reason in some languages second person pronouns are used for formal address and first person for familiar?