The association atheism had with Marxism was because Marx was an atheist and associated atheism with himself.
This association was continued by Lenin who associated atheism with Marxism-Leninism by also being an atheist and associating atheism with himself.
Maoism has an association with atheism because... Drum roll, you guessed it, Mao was an atheist and associated atheism with himself.
This concludes my TED Talk on: Why Marxism Atheism?
If you want the longer version as to why the material conditions of Industrial Europe, the Tsarist Russian Empire, and pre-revolutionary China were such that atheism and Marxism became inextricably linked, you'll have to read the figures themselves for the answer!
The association atheism had with Marxism was because Marx was an atheist and associated atheism with himself.
This association was continued by Lenin who associated atheism with Marxism-Leninism by also being an atheist and associating atheism with himself.
Maoism has an association with atheism because... Drum roll, you guessed it, Mao was an atheist and associated atheism with himself.
This concludes my TED Talk on: Why Marxism Atheism?
If you want the longer version as to why the material conditions of Industrial Europe, the Tsarist Russian Empire, and pre-revolutionary China were such that atheism and Marxism became inextricably linked, you'll have to read the figures themselves for the answer!