henotheism

There is one kind of oneness which does not exclude the idea of plurality; there is another which does. […] If, therefore, an expression had been given to that primitive intuition of the Deity, which is the mainspring of all later religion, it would have been—'There is a God,' but not yet 'There is but "One God."' The latter form of faith, the belief in One God, is properly called monotheism, whereas the term of henotheism would best express the faith in a single god.