And it is supposed not to be?
I beg to differ. There is nothing more arbitrary than beliefs about the existence of God, and they need have no meaning beyond the strict boundaries of the person proper.
So you arbitrarily don't believe that gods exist, and you have arbitrarily decided that all of the arguments in favor of god's existence are bad ones.
That really doesn't speak to the rationality of your position.
It says that it is not convincing to me. Which is the decisive factor, when the tire meets the tarmac.
Sure, we may add lots of arguments to both sides of the debate. But that changes nothing at the end of the day.
Then this means that theists have no need to take your assessment of their arguments seriously. It means that any reason for rejecting their arguments is permissible, from talking bananas to well-thought out rebuttals.
However, I don't really think the claim that "theists haven't met the burden of proof" is meant to be taken as a purely subjective standard, like someone's favorite color. When people do support it, they tend to use objective reasons, or at least, reasons that they think should be universally applied.
And if it is, as I stated from the beginning, that makes the whole "burden of proof" a completely pointless attribution.
In such a scenario, who cares if they have the burden of proof? It's a meaningless weight. If you can't be bothered to assess the proof offered, and indeed need to provide no other reason than "not convinced", then there is no reason for them to take the burden seriously.