I see what you're saying, but I think you've introduced a sleight-of-hand that you may not have noticed.

I know you're interested in explaining, but I want to go back to simply positing for the moment. I'm going to start by suggesting that when we posit something's existence, we don't have to explain how or why (or for that matter even if) it exists literally - we only have to explain why it's important for our mental model.

So again, we start by positing that there is something (i.e. the universe), rather than nothing. This is important for our mental model, because it's a prerequisite for future propositions; we need a canvas before we can add anything to it.

We posit other things like the Sun, the Earth, ourselves, and others. We posit both their existence and their rules for interacting with each other. These things are important to our mental model because they help us navigate the world from day to day. But again, we don't need to explain how or why these things exist or what they are literally. We just need to explain why we want to keep them as part of our mental model.

So we accept the sun, the Earth, etc. as useful propositions for our model. But what about God? You've suggested that the existence of God would help explain how and why the universe exists. But as I said at the beginning, that's not a question that needs to be answered for our model. Since you're not answering a question demanded by the model, God is not needed for this model, and is therefore not included.

But suppose that you reject my assumption that we don't need to explain the how and why all of the things in my model exist. And you contend that I do need to explain everything's origin. And so you work through all the things we've added to our model to explain their origins: You were created by your parents and a long line of ancestors who were ultimately created by the Earth. And the Earth and Sun were created by processes that started at the Big Bang.

And then you run into a problem, because you can't explain the origins of the big bang and the universe itself. So you posit that there is a God who created the universe. But then, you still have the problem of how / why God exists.

You see what happened there? My original model was fine, because I didn't demand an explanation of how / why the universe exists. But your model introduced a problem, because you insisted that we do need to explain how / why the universe exists. But when you added God to your model, it didn't actually make that problem go away.

So my argument, in the end, is that it's better to just stick with my model that doesn't demand that explanation, rather than try to use your model that does. Because your model always runs into that same issue of explaining the origination - with or without the God proposition.

Does that make sense?