One good indication is they are literally different, and mean different things.
It is a forgone conclusion that God exists. You are, without God. Atheos-Atheist.
A theist believes in God. That is the reality of our two positions.
You are assuming the thing you are trying to prove. A very basic logical fallacy.
That may be so, but how do you know it's true?
We never know for sure if something is true. We can only have degrees of confidence based on evidence.
I hope you don't make the mistake of tarring everyone with that same brush.
If you think you know something with certainty, I would ask how?
Relatively. That is, as confident as the knowledge that the sun will rise tomorrow, given that it has done so for at least 4 billion years. Which is to say, not absolutely certain.
How do you know what you want, when you don't even know whether or not you're a brain in a jar?
What is it that knows? And why can't that thing know other things?
I perceive that I want certain things, and that would be the case even if I were a brain in a jar. I think that the wanting entity is my physical body, but I could be wrong.
What is your definition of truth?
A correct model of existence, such that it is useful for making predictions.
You have no idea what the object of my desire is. Do you?
It seems obvious that you desire God to exist. If your definition of God is the universe itself, then, while even I believe the universe exists, you also desire to incorporate the ideology of various religions to the thing, making it something different entirely. And I would say it's confusing to call the universe a God, given all the religious baggage that goes along with that word. Science shows that the universe probably exists, and it doesn't require God as an explanation for anything, so it's superfluous.
According to you I am God.
You have no knowledge of what it is you are without, and as such your analysis becomes an excercise of speculation.
I claim you have no knowledge of the thing either.
At least with the notion of physical existence you can always jump back to this physical evidence thing, thereby instant, false, justification.
You deny empirical evidence for the thing you are trying to prove. At this point I could just dismiss your claim as without merit. What other evidence can there be? Being is physical. Nothing not physical exists.
Who do I need to show anything to?
You tell me, you choose to post here.
It is what it is. You are without God, and you always will be without God, until you accept God. Then there's a chance you can start to believe in God.
That's backwards. Give me a reason to think it's a real thing, not just a metaphor for the universe, and I will weigh the evidence.