From Wikipedia:
The Khmer Rouge had a policy of state atheism. Pol Pot, the leader of the Khmer Rouge and Prime Minister of Democratic Kampuchea, was an ardent atheist.
Replacing one religion for another (= communism, a state religion), isn't going to solve the problems.
If you think that what is wrong with North Korea, is "too much sceptical thinking", then you are just delusional.
These people aren't "atheist" because of rational sceptical reason. They are "atheist" because of a fundamental tendency for absolute power.
Communists typically do not want their subjects to be theists, because in a communist mindset, the State and the Dictator are to be the absolute authority. It's not that they merely "disbelieve" religions... It's that they don't want any competition in the title of "absolute authority". Which is exactly why communism is oftenly called a "state religion", where the dictator takes on the role of "god" in absolute authority.
You should inform yourself on, for example, the totally crazy things that North Koreans believe (or are required to believe) concerning their leader and his family....
Some examples... The official "belief" in North Korea is that the food aid they get from the international community is not just "aid" to a nation that suffers from hunger... Nope. The belief among the people is that that aid is a
gift from the international community because we fear and admire their leader.
Another thing they believe is that one the ancestors of Kim-jung actually
created the world.
To hold them up as examples of your "average atheist" is simply ridiculous.