Actually, the KR were sort of sui generis. They wanted to build a pure agrarian communist state. So, they did away with money, religion, private ownership of land, the entire education system, anything and anyone who had been part of the former government, down to very minor functionaries. They wanted to essentially dismantle the entire social structure and start over again from scratch. Hence, they referred to the first year of their rule as "Year Zero".<quoted text>
Kmer Rouge WAS a religion-- it acted >>exactly<< like all religions do-- it murdered any competition.
So you lose your argument.
They regarded anyone who grew up in earlier times with suspicion, as potential counter-revolutionaries because they remembered a different society. One of the first groups they slaughtered was the KR troops who owed loyalty to the former king. The king had been deposed in a coup sponsored by the CIA. He formed an alliance with the KR. Each group planned to eliminate the other after they jointly overthrew the US sponsored government. The original KR was much more ruthless than the royalists who joined to support the king, and the royalists were among the first casualties.
They were also ultra-nationalists. Even though the NVA and Viet Kong were also communists, and sent troops to help the KR fight the US backed Lon Nol Government, the KR still hated the Vietnamese.(Hatred of the Vietnamese has long roots in Cambodia, going back centuries. In fact, the usual Cambodian word for Vietnam/Vietnamese, "yuon" also means "barbarian". One of the big points of the current opposition parties is that the PM, Hun Sen, was originally installed by the Vietnamese when they invaded and drove the KR out of power.)
They also hated the US, and were paranoid about possible CIA attempts to overthrow them. No surprise there. Between 1965 and 1973, the US dropped over 2,500,000 tons of ordnance on Cambodia. Just for perspective, during WWII, all of the Allies dropped about 2,000,000 tons of bombs in all theaters, combined. It is even more remarkable when you consider that the US was not even at war with Cambodia during that time. The KR used the bombing, and their own virulently anti-American stance as a recruiting point.
So, crazy as they were, their delusions did not stem from religion. Nor, particularly from Karl Marx, although they claimed to be marxist. While they shared the common idea about ownership of the means of production, Marx would not have recognized much else in their ideas. Given the virulent anti-intellectualism of the KR, it is safe to say that if Marx had lived in Cambodia, the KR would have killed him.