It seems like the non-religous population is quite high in East Germany and the Czech Republic, supposedly due to the socialist policy of atheism. Why is this not the case in Poland? how was Poland able to stay to prominently Catholic?
You may be interested in my older answers to Why does the Czech Republic have so many atheists, yet Poland is so strongly Catholic? and Why did Europe become less religious over time and the US didn't? (x-post from /r/askreddit), and Why did Soviet policy of state secularism only have a lasting impact on East Germany, the Czech Republic, and Estonia?.