How many people have been killed as a result of christianity since it's inception, as compared to atheists?

I know hardcore christians always like to say that Mao, Stalin, and Pol Pot have killed so many people, and that it's all because they were atheist. Christianity has been around a lot longer. Are you absolutely positive that of all the years christianity has been around, that less people have died under all the christian tyrants combined?That the total number of people who were killed by christians and christian dogma numbered less than the people killed under communist leaders who were atheist? BTW i don't support communism, but saying that ATHEISM was responsible for the leaders behaving the way they did is just a shallow pretense. Christianity on the other hand is different. Christianity is a way of life, and all the christian tyrants used it to justify the millions of people killed.