As an athiest and Libertarian, I can assure you that there is plenty of blame to go around. No Christianity doesn't have such a good record. But they've been largely out of political power for a couple centuries now, so whether they've cleaned up their act or had it cleaned up for them, it is true that they haven't had buckets of blood on their hands lately.
Now it is true that there have been some athiest authoritarians like Stalin. But that's why you need a good political philosophy like Libertarianism. Atheism itself is just an acknowledgement that there is no creator entity. It isn't a life philosophy. Stalin had communism as his life philosophy. Well, we all know where that leads -- same place as fanatic religionism -- to the slaughter.
There is room in Libertarianism for both theists and atheists -- it is a political philosophy of maximum freedom and tolerance. That doesn't sit well with communists or fanatical religionists. But it works just fine for the rest of us.
Curious. Why have some of the most vicious posts I've received come from "tolerant" Libertarians? All I have to do is turn on "Politically Incorrect" to hear more?
I agree that there are some good philosophies in Libertarianism. But, there are some smelly ones too.
As to tolerance, your own post in favor of Libertarianism smacks of intolerance to Christians. The "buckets of blood" comment was hardly neutral.