The unspoken assumption behind this is that atheists aren't human. Though, having said all that, their findings do disprove this obvious nonsense. I think perhaps we would have noticed if half of our population were psychopaths.
In England, yes. But in the good ol' US of A we already know more than half our population are psychopaths. Christian psychopaths. It's part of our culture.
Here atheists are not treated as aliens, non-human. We are treated as heretics. Traitors to their god. Lost souls controlled by demons walking in their sacred midst.
BTW. Did you really expect anything different from the Vatican?