Why are you a theist?

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The existence of the universe is just one line of evidence. For humans to exist gravity at an exacting strength has to exist, the laws of physics that can turn hydrogen and helium into the type of matter we need to exist. Stars, planets, solar systems, dark energy, dark matter, the molecule Carbon and oxygen and water to name a few. All by forces that didn't care or intend stars and planets or even the universe itself to exist. Nature doesn't need any of these things to exist...only we humans do.

What's your evidence that natural mindless forces could without intent or plan could cause a universe with the exacting conditions for humans to exist?

Why are you looking at this as "for humans to exist"? It could well be that humans can only exist with these exact or similar natural forces and properties that we have in this universe. But I don't find that in and of itself to be strong evidence for intention in this universe's creation. I would really only find this persuasive if it could be shown the values of the natural forces in this universe are the only ones which would result in complex life at all or that there is a particular reason that humans are specifically more special than complex life that could form under other conditions.

I don't claim to be an expert or to have studied this too in depth, but there's nothing I see in this thread or in my other brushes with the fine-tuning argument that has been persuasive as to those points.