Dear egrant,

I'd like to offer a more pragmatic answer to your question.

You should ask yourself two questions: (1) How would you deem, whether a definition of "God" is satisfactory? (2) How would you deem, whether a verdict on the matter of the existence of God is correct? Answers to both of these questions are prerequisite for you to be able to profit at all from answers to your original questions. Nobody can answer questions (1) and (2) for you except yourself. It may not be easy for you to answer these questions, but unless you do so, there is really no use in proceeding to finding answers to your original questions.

Now, "God" is a word, and you inquire of the meaning of this word. Words are rarely used out of context. Where have you encountered this word? Firstly, try to assemble a list of citations that use this word. Make sure, that each of these citations was made by a person who lives today, who you can address a letter to. Next, address a letter to those people, and ask them what *they* meant by "God" when they made those citations.

Suppose you receive a satisfactory answer from one of your correspondents, say "God is an XYZ". Now you'll want to know whether such an XYZ exist. You will need to address this question to somebody, possibly, but not necessarily, the one who provided you with this definition. The authority who you should consult depends really on the nature of the answer you receive to your first question, and on your answer to self-directed question (2) mentioned above.

Good luck!