Man... this discussion is really... deep.
I can understand where you're coming from with the whole definition thing. I had an almost exactly similar issue on the definition of bronies (and both you and I seem to be one).
One of my friends, whose username is actually *
TheIrishBrony, decided
he wasn't a brony anymore, but still watching the show. I tried to explain that to him that by being a male and watching the show, he was, by definition, a brony. He didn't buy it and said "it depends on your definition". The reason he didn't want to be identified as a brony is because he didn't want to be associated with the rabid fandom/stereotypes and cloppers, etc.
I was moved enough by this issue that I wrote a whole journal about the definition of bronies. Want a link?
But then on the other hand, it's partially true, even with it comes in conflict with popular views. Dictionaries attempt to be a guideline regulate language, not be the dictator of language. We didn't freak out when "gay" went from meaning happy to homosexual or when "bitch" went from female dog to approximately a slutty human female.
Your dictionary, again, isn't the central authority of the English language. Language is made by human minds, not by bureaucrats. It can be regulated and we can try to keep definitions the same, but not forever. If you were the last English-speaker on Earth and told your kids that you were a light brunette, having no regulating society or dictionary to turn to, they would probably believe you. If the word "brony" somehow evolves to mean "male fan of MLP" to "man who faps to ponies", it would be indeed unfortunate, but it's totally possible of happening. It's probably because the fact that we don't want definitions to change is the exact reason that we can get so caught up in enforcing them, but this only goes so far.
I'm not exactly saying we can't try to give a lexical definition of God because the concept is beyond us, either. Think about it. Christians will almost certainly define God in a different way than Muslims or Jews, no matter how slight. Thus the study of theology. True, God may be associated with religion, but what if both the definition of God and religion changes?
Anyway, let me give you the Webster's II New Riverside University Dictionary definition of God.
God a. A being conceived as the perfect, omnipotent, omniscient, originator and ruler of the universe, the principal object of faith and worship in monotheistic religions.
b. The force, effect, or manifestation or aspect of this being.
c. Used to refer to <"Infinite Mind, Spirit, Soul, Principle, Life, Truth, Love" -Mary Baker Eddy>
2. A being of supernatural powers or attributes, believed in and worshiped by people, esp. a male deity held to control some part of nature or reality.
3. And image of a supernatural being/idol.
4. Something worshipped or idealized.
5. A very handsome man.</b>
I'm supposed to use common sense when naming and defining things, but I'm not forced to use a certain definition, either.