Have You Ever Cursed God?

[AFTT47]

I've done it a few times with people who believed my atheism was a scam, a form of rebellion and that I knew God existed in my heart. Always a horrified reaction from the theist but of course, no lightning or change of luck.

I don't know what you mean by, "Do you think cursing god publicly is the sine qua non or touchstone of a true atheist?" It certainly gets the point across that you are indeed an atheist.