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

[masterofpuppets]

The bad news is that you will keep on floating in this material universe until you will start use logic and start thinking that a creation must have a creator.

Actually, logic can't get me to start thinking that the Universe is a "creation" and that there must be a "creator".

The good news instead is that God can not possibly punish anyone even if the karma law is there as a way
to teach and sort out problems.
You just punish yourself by not following logic.
In any case at the end when the lesson will be learn everybody will become part and parcel of the ocean of cosmic bliss.
No hell exist except the mental hell that we create by not using logic.  

This wall of text is completely void of content at best and asinine at worst. However, I regard your positive notions as not being so deplorable.