First of all, I am glad to see that Aurino is back. Since he and I seem to see eye-to-eye on most ideas that I think are important, it is fortunate for me that he has re-appeared during a time when I am short of time for responding.
***Why stop at defining God?***
That's an interesting question, but regardless of whether or not there are reasons to stop there, it has no bearing on my suggestion. My suggestion was to start by defining God. I don't really care if we stop there or continue beyond, defining more terms.
Consider for a moment, the question of "How many angels can dance on the head of a pin?" If we were going to seriously work on resolving this question, we would not quibble about, and demand definitions for, the words 'pin', 'head', 'dance', or 'how many'. The real problem with this question is "What in the heck is an Angel?"
So I maintain that an agreed-upon definition of God is absolutely necessary before we can work on the question of God's existence, otherwise we would be engaging in nothing but meaningless blather. (Not that we occasionally don't as it is.)
Some time ago, as you may remember, it occurred to me that it might be possible to distill the essence of the various God-concepts in a way that would meet with wide agreement. With my meager knowledge of the world's religious precepts, and with the knowledge of the opinions of several people on the Counterbalance Forum, I made such an attempt.
I thought that everyone would agree that God was at least a transcendent sentience. Boy, was I wrong.
If you remember, I challenged each participant of that forum at the time to tell me why that definition was not at least a necessary condition for their concept of God. With the possible exception of Aurino (I can't remember if he responded or not) I didn't get a single agreement.
Alan responded that it might be better to call a spade a spade rather than trying to make one definition fit all. I think he must have a god-concept which is self-evident to him and which was not exactly consistent with a transcendent sentience.
Your response, Harv, if I remember right indicated that you were reluctant to attribute sentience to God. You weren't sure that God did anything quite as human as thinking but that he was probably more like an abstract principle.
And on it went. People either denied the attributes of sentience or transcendence, or they insisted that these weren't as important as other attributes like perfection, infinity, omnipotence, omniscience, love, inscrutability, a throne in the clouds, a white beard, or whatever.
If one is specific about how one defines God, then I think that it might help to define the rest of the terms in the original question. But I think that a meaningful job can be done by simply assuming the vernacular definitions of those other terms. Defining 'proof' might be more or less sticky depending on the person's view of God.
For example, if some person's definition of God were some particular stone statue, then the method of proof that that particular stone statue exists might be different from that of a definition of God as an abstract principle.
Another example was Lars' definition of God as "That about which nothing can be said." In this case, it is easy to answer the original question. The answer is that the existence of this God cannot be proved, at least in language. For in order to prove God's existence, we could hardly avoid saying something about God, which cannot be done by definition.
So I maintain that each separate attribute which may or may not be attributed to God will affect to some extent the arguments that might bring some light to bear on the question of existence.
Therefore, I am still interested in hearing Michael's definition of God, and I think we can give him no help with his question until he does.