At the core of Rosh HaShanah and its liturgy is the notion that God is being coronated.  This is the day that we declare God as our king.  But why it is that the King needs to be coronated anew each year?  Kings do not have term limits.  God never steps down from the throne. Nevertheless, we coronate God annually.  We do this because, even though God does not change, we do.  We change and so does the world we participate in.  Existence is not the same as it was last year, and therefore even though God is the same God, He needs to be declared king over this new world and recognized fully as the author of this new stage of creation.