You have just shown that there is something in common with those evil persons within 3 different groups that are apposed to one another in doctrine and beliefs. Here's how I would properly write your sentence: There is no question that insane Christians and insane Muslims and insane Atheists have mastered the art of murder. In the 20th century and part of the 21st century, who were the insane Christians and insane Muslims? Mao, Stalin, Hitler were Atheists. Hitler thought Aryans were descendants of aliens from another world who landed here 40,000 years ago and were white powerful beings. So, the common thread is "insanity." Most Christians are not this. Most Muslims are not this. Most Atheists are not this.
I would disagree also on using the word, insanity as the reason for the actions of Mao, Stalin and Hitler. Their actions were derived by a thirst for power and wealth. They used communism and fascism as modes to gain control over their people. Poverty within their countries was used to find scapegoats to kill in order to regain control over their financial troubles in their countries. While the United States has used capitalism with a welfare net to accomplish this. However, in the U.S. people like Margaret Sanger saw eugenics and abortion as a way to reduce poverty amongst blacks in the ghettos. The Democrat Party today is doing the same thing moving ever so close to communist tyranny because they refuse to use capitalism. Instead, they punish capitalism and promote socialism. Bill Ayers of the Weather Underground in the 60's and 70's communist movement was heard to say by the mole, Larry Grathwohl, that they want to tear down the capitalist U.S. and may have to kill 10% of the population that will not be brainwashed in their re-education camps. That's 33 million people today that these insane people are ready to wipe out. We see some of this in our education system with CTR and gender confusion camps called the government school system. All Atheists and all insane.
