Why are all atheists liberals?

[Dystopia]

So you are the average liberal or social-liberal (someone who advocates the free market with state responsibility with the disadvantaged + social justice) - I'm not even saying you're wrong, but the socialist argument (I just feel like sharing what my socialist friends say) is that capitalism will always be oppressive because even if you reform it away from oppression the rich continue to pass their wealth inside families, finding ways to evade the system and have the power to lobby with the government, force privatizations, exploit third world countries, create crisis, etc - So the basic argument is that any social justice will fail until you overthrown capitalism.