I think the Khmer Rouge was a religious organisation (Belief in god is not essential) what is required, is blind faith in defiance of the evidence.
The 20th century was plagued by two mutually exclusive and incorrect religious dogmas one that human nature is only genetically determined and on the other that human nature is purely a social construct.
Whilst the first of these has been demonstrated to be false the second is still alive and well in the sudo-sciences such as sociology were the creed of absolute relativism is incanted every day.

PP