"I already acknowledged that they were atheists, I never denied that. What I'm saying is if they did the bad stuff they did because they were atheists then how come atheists haven't been doing stuff like that for thousands of years?"
Probably because atheism hasn't been around for very long and remains one of the smallest minorities of belief in history. There have been relatively few experiments where atheists take full power, but of those experiments, it ended in the most brutal dictatorships in the history of man.
On the reverse side, we've had Christian kingdoms for literally 2000 years, and yeah, there have been bad people in them. Just downright bad guys that needed to face justice, won't deny that. Can't deny that, but the amount of tyrannical dictatorships that Christianity has created is almost non-existent when compared to the atheist ones and in a shorter amount of time.
"I could say the same thing about believing in God. People who believe in God have committed the worst human rights violations in the history of mankind."
I mean that's a relative scale, but to further make my point; you've been having to go back to the Middle Ages to find oppression in the name of Christianity while I just basically have to go back to when my dad was a kid to find examples of atheism stomping on the rights of a country's people.
"Except not everybody who helped usher in a better way of looking at the world were Christians. And if we go back to the Enlightenment at the start of that, those people were often nonreligious"
Vice versa, my propagandist. Not everybody who helped usher in a better way of looking at the world was nonreligious and even fewer atheists. It appears that the minority of golden-age scientists were non-religious/atheist. Whereas the list of the most celebrated thinkers of that exact time that ushered in the age of modern thinking was almost exclusively religious in some way. A LOT of whom were Christian. And that's a fact that doesn't go away just because it frustrates you.