Since your reference claims that atheism was the cause of those examples of violence against humanity, does it actually show a causal link between the two?
I could just as easily point out that the overwhelming majority of convicted murderers in the US are Christians and claimed to be so before they committed their crimes. So what? I can't link their religion to their actions any more than your so-called researcher can link atheism with inhumane behavior.
Now if you want to use statistics, it is well known that the percentage of all atheists that commit crimes is lower than the percentage of all Christians that commit crimes. Can I say that atheism leads to more proper behavior? Absolutely not!! That statistic alone doesn't take into account a myriad of other possible influences on the behavior of the people in the study.

Basically, the claim, implied or otherwise, that atheism leads to the type of behavior described in those two passionately written paragraphs is bunk. Being adamant about it doesn't change it from the bunk that it is.