Just so you know, the CSMONITOR is not an unbiased source and that was not the reason those fine upstanding gents did what they did.
Russia:
Even before the end of the civil war and the establishment of the Soviet Union, the Russian Orthodox Church came under persecution of the secular Communist government. The Soviet government stood on a platform of militant atheism, viewing the church as a "counterrevolutionary" organization and an independent voice with a great influence in society. While the Soviet Union officially claimed religious toleration, in practice the government discouraged organized religion and did everything possible to remove religious influence from Soviet society.
Thousands of churches and monasteries were taken over by the government and either destroyed or used as warehouses, recreation centers, "museums of atheism", or even GULAGs. To build a new church was impossible. The sixth sector of the OGPU, led by Eugene Tuchkov, began aggressively arresting and executing bishops, priests, and devout worshippers, such as Metropolitan Veniamin in Petrograd in 1922 for refusing to accede to the demand to hand in church valuables (including sacred relics. Many thousands of victims of persecution became recognized in a special canon of saints known as the "new martyrs and confessors of Russia".
Practising Orthodox Christians were restricted from prominent careers and membership in communist organizations (the party, the Komsomol). Anti-religious propaganda was openly sponsored and encouraged by the government, which the Church was not given an opportunity to publicly respond to. The government youth organization, the Komsomol, encouraged its members to vandalize Orthodox Churches and harrass worshippers. Seminaries were closed down, and the church was restricted from using the press
http://en.wikipedia.org/wiki/Russian_Orthodox_Church
China:
From 1959 through the late 1970s, Chinese authorities methodically sought to destroy most aspects of Tibetan Buddhism. At the height of the Cultural Revolution, the Party intended to eradicate religious belief and practice in Tibet and committed acts of genocide. Over six thousand monasteries and temples were destroyed, dismantling the entire monastic system of Tibet. Tens of thousands of monks and nuns were executed, sent to concentration camps or sent back to their villages. All religious activity was banned.
"This Communist Chinese view was all-pervasive. In Mao Zedong's own words, "... but of course, religion is poison. It has two great defects: It undermines the race ...(and) retards the progress of the country. Tibet and Mongolia have both been poisoned by it.""
"By the middle of the 1950s, the Chinese authorities realised that religion was the principal obstacle to their control of Tibet. Therefore, from the beginning of 1956, a so-called "Democratic Reform" was carried out, first in Kham and Amdo, and later (in 1959) in Central Tibet. Monasteries, temples, and cultural centres were systematically looted of all articles of value and then dismantled."
http://www.tibet.com/WhitePaper/white7.html
Cambodia:
" Between 1975 and early 1979, Pol Pot and Leng Sary led the Khmer Rouge – the Communist government of Cambodia. Their government turned Cambodia, which it called Democratic Kampuchea, into the “killing fields.” The Khmer Rouge emptied all cities and towns, sending the entire urban population to the country side to farm the land and be “re-educated.” They banned all institutions, including stores, banks, hospitals, schools, religion, and the family.
Dissenters were brutally executed. Teachers, doctors, lawyers, artists, and just about anybody with an education were killed. Hundreds of thousands starved or died of disease. During a four year period, more than 2 million people died; almost one third the 1975 population of Cambodia."
http://www.globalsolutions.org/programs/law_justice/faqs/cambodia_factsheet.html
Germany:
Hitler focused his propaganda against the Versailles Treaty, the "November criminals," the Marxists and the visible, internal enemy No. 1, the "Jew," who was responsible for all Germany's domestic problems. In the twenty-five-point programme of the NSDAP announced on 24 February 1920, the exclusion of the Jews from the Volk community, the myth of Aryan race supremacy and extreme nationalism were combined with "socialistic" ideas of profit-sharing and nationalization inspired by ideologues like Gottfried Feder. Hitler's first written utterance on political questions dating from this period emphasized that what he called "the anti-Semitism of reason" must lead "to the systematic combating and elimination of Jewish privileges. Its ultimate goal must implacably be the total removal of the Jews."
http://www.jewishvirtuallibrary.org/jsource/Holocaust/hitler.html
The emergence of eugenics as an ‘applied science’ culminated in the horrendous atrocities committed by the Nazis during the Third Reich. Society was to be cleaned of all alien contamination, hence the German phrase ‘Rassenhygiene’ meaning ‘racial hygiene’. Jews, gypsies, homosexuals and people with hereditary diseases were deprived of their human rights, herded into concentration camps, used for scientific experimentation and murdered. And the scientists who provided the scientific backing were respected university professors or researchers of the Kaiser Wilhelm Society (KWS), the predecessor of the Max Planck Society. Many of them remained in renowned positions even after 1945, influential enough to delay an unbiased historical confrontation.
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1084095
Tally:
Chinese Communists -> 65 million dead, 40 year period - Economic ideology, not religion
Cambodian Commies -> 2 million dead, 5 year period - Economic ideology, not religion
Soviet (Russian)Commies ->20 mill dead, 50 year period -Economic ideology, not religion
Germany ->60 mill dead -- 8 years- racism, imperialism, not religion.