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

[SteveII]

1. I would say that questions like "how did religion evolve" and "how did morality evolve" cannot have scientific answers -- because nothing that resembles the scientific method can be applied to them. So, theories are advanced that, at best, are plausible. That is a very low standard. 
2. No, they really can't -- just like the naturalistic theories.

1. Actually, they can and do have scientific answers. In regard to your example questions, one can make observations, test candidate hypotheses and then derive explanations for the evolution of religion and morality.
2. Naturalistic theories are built upon falsifiability. What you have said is simply false.

1. Then explain just one from the two examples.
2. No, again, not when we are talking about how this or that characteristic or psychological trait may or may not have evolved. If you think so, give an example.