Poland is so religious mainly due to our history - We were always at the front or something or other, which was often religious in nature.
Let me explain. When Poland was born as a nation, we were on the eastern flank of Christianity. To the east we had a whole bunch of pagans. Russia was baptised shortly after Poland, but they took on the Byzantine/Orthodox version of Christianity. Poland became the eastern flank of Catholicism.
When the Mongols took over Russia, and later the Ottomans took over most of the Balkans, the Polish state again found itself at the flanks of Christianity - bordering Islam.
When Protestantism took over much of Europe, Poland remained one of the only Catholic countries in the region.
Our neighbours were often different from us in terms of religion, due to our "being on the flanks" like I explained above - Catholicism thus became an important aspect of our identity.
When Poland was erased from the map in the late 18th century, Poles needed something to hold on to, something to give them hope - religion filled the role perfectly. When the Soviets took over our country after ww2, the Catholic church became a unifying force for all Poles. It was something we all had in common, it gave us hope, and the fact that the Pope was Polish didn't hurt. The fact that this religion is what held us together in the past, in our crazy history, while neighbours-who-practiced-different-religions tried to take us down, had a big part in the mentality of what happened in the 1980s, too.
Anyway, that's my take on it. Czech history is incredibly different from ours - I'm sure Winner or somebody else will explain it in a lot of detail. Personally I am inclined to believe that it has something to do with different religions coming in at different times - and people getting sick of false promises.
I mean, in Poland you have one religion unifying Poles and giving people hope over a thousand years, while in Czechia it was more a case of people coming and saying: "Here, try this religion!", and people eventually getting fed up with it and developing a skeptical view of religion. Correct me if that's not what happened at all, as I have an amateur-level understanding of Czech history at best
You in the past could actually just go to Ukraine and ask random people if they are catholic or orthadox and than you know several facts: Catholic's were poles, Orthadox were Ukrainians, Catholics (and poles in general) tended to be upper class citizens while Ukrainians, Belarussians and Lithuanians tended to be lower class, among other things.
