Yes, millions have suffered. Again, the most important question is the rate, and comparing rates between groups. Christianity is the biggest religion; with such a large base, even if Christians are cruel at the same rates as other groups, the overall number would be the largest, and while that wouldn't be consistent with Christianity's internal message, it wouldn't be an indictment of Christianity in particular either. But considering that Socialism/Communism has killed far more people than Christians have and on a smaller basis, making a much larger rate, Socialism/Communism is the most evil. All the purges Stalin did, all the famines and purges Mao Zedong did, the Khmer Rouge, and the Nazis who were neo-pagan Socialists: https://www.historyonthenet.com/20-hitler-christian-atheist-something-else-richard-weikart