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

[RoadRunner79]

In these arguments... no I am not advancing a specific book or tradition. Mostly because it doesn't follow from the argument.

Getting back to the fine-tuning argument, RR79...I'd like to know your thoughts about another way of looking at it. Now the typical approach is to think how very lucky we are that every thing is just so. But what if this universe is actually rather unfortunate for life. Clearly the vast enormity of the universe is 99.999999999999999999% inhospitable to life as we know it.  And as far as we know, we are alone or at the very least life is so spread apart that we might as well be alone. What if this universe lacks some wonderful "Felicity constant" or "Law of Winsomeness" that would have made, not widely-spaced stars and planets; but rather, some ubiquitous ether teaming with plasma creatures of living light? Why do we assume that alternative universes would be worse? Might they not also be better?

Personally, that sounds  a lot like the boltzman brain conversation (if I'm understanding you correctly).   I've never delved into that too much; I feel it gets a little too far away from it's foundation, for me (building on assumptions without backing as you go up the line).  But I do think that the fine tuning argument is working off the math from what we know about this universe and it's physics.

I may need to think about your question a little more.