> not sure if westerners are aware but communist were against any religion

They were trying to fight it for a while, but catholicism in Poland was too strong so they formed a kind of cease fire. That's why they even let people build churches, do mass celebrations, pilgrimages etc.

And a lot of priests were secret informators of the security (communists searched for any material for blackmail and if they found something they forced them to become informators - common blackmail material was pedophilia and homosexualism (treated so because of social stigma) ).