Atheists get a bad name, and a lot people seem to think many major tyrants in history where atheists. I am going to try and set the record straight here.
Atheists are given a bad name by the nature of our values and how we go about with them. I admit I am a very aggressive atheist when it comes to discussing religion, but I have seen the harms of religion first hand, and what religion can do to others. I have seen kids shunned and told they are worthless by religious people because they where gay, because they where not going to church, because they believed in a different abrahamic god. I have seen this first hand, I used to think this was acceptable when I was a christian, I realize now what a terrible person I was. When Atheists try and call out religion for being this way they automatically think it is religious persecution and curl up and get defensive. This is way things are regardless of how we as atheists behave. They are assuming they are a minority even though 10% of the US is non religious and even less identify as atheist.
Now, for major tyrants in history, Hitler is normally called an atheist, but a lot of his speeches he talked about the teachings of Jesus Christ. Religion was important to him and his views, which does match up with the many biblical mass genocides. Another one is Stalin, all I am going to say about Stalin is the Russian Orthodox church had a firm grip on the USSR for most of its existence.