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

[RoadRunner79]

When I was a theist, the most compelling argument I ever heard for atheism was, "Read the bible fully."

Personally, people who read the canon in order from start to finish are ill-advised. That may leave you with a basic biblical timeline, which is a good thing, but also leads to much confusion. The texts have to be read both forwards and backwards to draw out all the foreshadowing and typology. My favorite technique is finding a common phrase, consulting a concordance, and then comparing how it is used in each instance. The texts open up in unexpected ways to reveal hidden themes and allusions threading their way through the narrative. These threads tie the stories together just as Jesus said, "If you believed Moses then you would believe me..." (John 5:46) I find that approach more helpful than the typical topical approaches most bible study groups use. Those seem more like proof-texting clubs. I'd be happy to share videos of some study groups that take that approach, albeit from a Swedenborgian perspective, for anyone who is interested.

I would disagree here somewhat.... I do think that reading straight through, has value, in providing perspective and context.  This helped me out a great deal, to understand the why throughout the story.  But I also do agree with a systematic approach, for doctrine; as well as  other tools such as you mentioned, comparing how words or phrases are used.  Also you can look at cultural context, as well as if there is commentary from that time or the orthodox view. 

I think that it takes a balanced approach, and I try not to focus too much on any particular tool (they each have their uses).  And while I do agree, that there are some hidden themes and allusions (which may not be obvious from a casual reading), I have also seen some wackos who seek for hidden themes and allusions a little too much.