I don't believe I've met anyone who thinks atheists are evil, so I can only take a poke in the dark. Few may think this way because if you don't believe in Christ, then you are antichrist, and prevent not only yourself but others from being "saved." Or it may be because without an objective moral compass, the idea of the existence of good and evil results in indifference, allowing for violent acts to be carried out under the guise of hard cold reasoning, take for example eugenics. If this world reached a population growth where the production of food supply couldn't sustain a healthy environment, then it would be argued it rational to kill off a few people, for the sake of survival. The members of the X club Darwin, Thomas Huxley etc, (also the Luna society), believed themselves to be far superior in intellect than the gross populace of common people, not only did this lead to them interbreeding with each other, (much like the Royals) but also of the belief that there would always remain a higher need of war, poverty and disease to keep the numbers of less savoury "common folk" (a special dislike of black people and Irish, in order to make sure they didn't breed the "more intellectual out of existence. The likes of Margaret Sanger also was very keen to improve on effectiveness of culling the unpopular race and class by bringing in abortion clinics, which Bill Gates (a computer nerd) and wife also went on to promote. Many people do not look at the murky side of eugenics and its original purpose, Hitler was a eugenicist, and the Nazis were sent overseas to America to carry on their eugenics and mind control projects such as MK Ultra.

China has a high percentage of Atheists at 91%. Since 1949, the Chinese Communist Party officially stated that Atheism has been in power in the country, and prohibits party members from religious practice while in office. Only churches authorized by the government are allowed to operate. In reality, many Christians worship in unauthorized venues known as "underground churches." It is evil for the Chinese government to oppress religious freedom: https://youtu.be/xbV76bcgmGU?si=6lq2Ddx1wSJTAWIZ