When you hear from your family: 'you are a f#cking communist, just like your father!' because you happen to be [too?] liberal. Yes, I read about the feminist movement, pro-choice and atheism, but I am not a fully left-wing person.
I think this is one of the simplest explanations (a republican channel here, yes)
https://www.youtube.com/watch?v=tlIjMJBSnRE
As an atheist myself, my atheist friends have been all over the political spectrum. I've talked to left-leaning, right-leaning, centrist, Communist, and apolitical atheists.
The trouble in Eastern Europe is that for many people you are still either a revolutionary commie wishing to take the next train to Russia or a square pro-West and you dream about being an American. Being liberal is like sitting in a dense fog.
What you said above is the broader view.
Not really a broad view, just my personal experiences. My conservative atheist friends have discussed their harassment. Liberal atheists sometimes (maybe often) think atheists must be liberal. The fact is that atheism is just one thought and has nothing to do with anything else. Just no belief in gods. Has nothing to do with politics, just religion.