>> Are/were the majority of the people in these countries atheists? <<
Some yes, some no. My point is only that atheists had to resort to brutal terror to impose themselves. So the issue of whether the majorities were atheist or not is moot, unless you plan to make the argument that Hitler, Stalin and Napoleon would've been tolerable, had only the people submitted themselves to their rule more willingly.
I don't plan on making any arguement.