Like the word love, god is a complex and evolving concept disguised as a tiny word that people use under the misguided assumption that everyone will interpret it the same way they do. It's a bit of a throwaway word really, like plant. It describes a thing super vaguely instead of specifically the thing in question.
It's no wonder people love to argue about it, really.
Ideas about what god is or isn't can be either essential to a person's worldview, or completely irrelevant to it. In either case, such strong beliefs are things we us to define ourselves. And to some people, opposition to one's beliefs or view of the world is seen as a threat.
But why? Is variance not practically inevitable when dealing with a word so ambiguous?
I think instead of trying to nail down a definition, people would be either completely uninterested, or if not at least open to the idea that a god concept can be many different things, some they may not have considered.
I think that's why so many are religious (in a sense) about science instead of god. It is something that can be verified to the point where a person can feel sure about it....sure that their worldview is as accurate as possible by means of an agreed upon process...it's all very sterile and unfeeling.
But hey, it's factual so it's got that going for it.