Theists: What is the most compelling argument you have heard for Atheism?

[Mister Agenda]

Except that, for all we know, they're all black balls.

Not to strain the analogy, but that would be all the more fine-tuning.

(then of course there is the universe of all blue balls...not anyone's favorite)

Or they're black (or blue) of necessity. Or it could be even up. Or any combination. When we don't know the odds, we can't say the odds are slim.

I could win a lot of money from some folks around here who seem to be eager to bet on the outcome of a ball drawing knowing nothing except that the set of balls to be drawn from has at least one black one.