No; communism isn’t like atheism at all. Communism is a belief system; atheism is the lack of a particular belief. You might as well blame the evils of Christianity on Christians generally not believing in elves. And if atheism was the problem, where are the non-communist atheistic tyrannies? The religious hatemongers keep trying to pretend atheism = communism because that’s all they have.
As opposed to religion; you don’t need to restrict yourself to a single sect to criticize religion. If I were to use the behavior of the Catholic Church to explain why I consider religion destructive, no one can refute that with “oh, that’s just Catholics” since I could then just make the same criticisms using examples from entirely different religions.
Wow. When you say “atheism”, do you include “agnosticism” and “irreligiosity” too? Not really sure if you mean “strong atheism” or “weak atheism”. Your voice, I presume, would match that of a strong atheist.