You can define a concept any way you choose

That isn't exactly what I mean. You can't define a cat to be a horse, but you can define a cat to be a feline, or a house-cat, a Caterpillar machine, etc. You see, there's one label for an array of meanings. This is why I gave the example of 'dad', there are different ways you can take the word. You can define a concept in different ways, so long as they make sense.

I agree it's very important to be on the same page, that's why I've written all of this. Not to say that I can call whatever I want God, but to say that if we're on the same page, you will agree that it is impossible for God not to exist. See, even if tiger and house cat are both valid examples of a cat, we can't have a conversation about cat unless we agree on the definition.

I don't want to backtrack, so I'll submit that what I said was incorrect. But, perhaps we can move forward regardless.

I do believe that God is the totality of things. But, that isn't where I want to start, that is just proof that God exists if you accept that definition. What I do think could progress our mutual understanding, is bridging the gap between that definition, and the one you're familiar with.

God is the creator of all that is. I think this much, we can agree on, right? Whether or not it exists, that is what God means to us. If you disagree, I would like to hear your definition, so that we have a common starting point. Existence is certain, there is no question of that. The proof is in itself, existence is happening. There are two options for its origin, ie its creation: either it was created at a point in time, or it has always existed. If it was created at a point in time, it is impossible for it not to have a creator. Whatever created it at that point in time, is its creator, is God. If it has always existed, it must have created itself at the beginning of time.

You may be wondering: why do you say that it must have been created, instead of saying that it was never created, since it always existed? My answer to that, is because time began. If time began, then the universe began. The universe could not have existed before time, because the universe is contained in space-time. Without time, there is no container for the universe to fill. Imagine a cup of water, before cups existed. It doesn't work. Imagine (liquid) water, before liquid was possible. You just can't do it.

So, if time began, totality began. If totality began, it was created. If totality is all there is, there was nothing else to create it, but itself.

The question left is whether or not time began. We have an approximation for the age of the universe, just under 13.8 billion years. I can't pretend to understand why we have this number, so I can't say it must be correct. However, if the big bang theory is at all close to a representation of what happened, what is happening, then time beginning is a logical conclusion. Everything exploded, but it must have exploded from something. One thing. The singularity. Before the explosion, is before time. Hence, at the beginning of the explosion, you will find the beginning of time. I don't believe it will ever be possible to say "the universe began exactly this amount of time ago", but I DO think that we can say "the universe did not exist 20 billion years ago". For a somewhat abstract example, Pi definitely exists, we use it all the time. We can't say exactly what it is numerically, but we can say it's more than 3 and less than 4, definitely.

I tried to be as linear as possible with this explanation. If you disagree with some conclusion I've made, let's discuss this further. I am certain, that reason alone is enough to prove the existence of God, assuming a fundamental definition (ie not "a fitting entity for descriptions in christianity").