Atheism isn’t a positive set of beliefs. In other words, there isn’t a list of things that atheists do believe, only a list with one item then don’t believe.
Comparing Stalin to Voltaire because neither believe in god is like comparing Gandhi to Pol Pot because neither believe in leprechauns.
I think Voltaire would have agreed with Stalin on most things.
Hatred of religion is a mark of a deep insanity.