Can I first note what it says that you don't immediately understand where this is going? And ask, why do you think that is? I only say this because people seem to have a very difficult time understanding the linguistic concept of definition of terms. I'm not quite sure why that is, I suppose probably simply taking language (especially abstracts) for granted, presuming that every abstract word only ever means what they think it means to themselves. At any rate, it's a basic concept of both logic and reason, upon which all meaningful thought (or, ability to think meaningfully) is founded. It is the fact that most do not comprehend this basic understanding which allows me to discern that most people have not yet become able to accomplish even the most basic forms of meaningful thought.
Now, first suppose a sun worshipper says to you "God is the sun" - then you would understand (hopefully) that everyone is a theist in relation to his proposed deity, yes?
Suppose next a natural pantheist says to you "God is the sum of all natural processes" - then you understand by his definition, you are a theist in respect to his deity, yes?
Now, suppose I say "God is the sum of all consciousness". You are a theist then in regards to this definition, yes? God is proven relative to each definition.
Now suppose I define the "Biblical God" as "the sum of the transformative information conveyed through the words of the bible". Again, you see that I have proven God by definition. In fact, in all of these definitions, both atheism and agnosticism become impossibilities.