I will prove to you that God exists

[Sheldon]

(Bold mine)

I disagree. I have no doubt that gods do not exist. I may be wrong, but I’m not uncertain.

Boru

I'm a theist but I'm not 100% sure. How can anyone be certain how a universe that caused intelligent life to exist was caused inadvertently by mindless natural forces? Do we 'know' such forces alone could do that? Do we know they did do that? Where does your certainty come from?

Natural phenomena exist as an objective fact, we already know they are possible beyond any reasonable doubt. You are the one adding inexplicable magic, from a deity you can demonstrate no objective evidence is even possible. And you are still, using an argumentum ad ignorantiam fallacy by suggesting there is any truth to the claim the universe required a creator, because we can't offer an alternative explanation. Atheism is not a claim, it is disbelieving a claim, and it therefore has no burden of proof.