I don't know why, but Polish people are the most religious community I know here.
Historical reasons basically.
For the most part of the past 200 years, Poles lacked their own independent country (first it was partitioned in 1795 by Russia, Prussia and Austria, then it gained indepenence in 1918 only to be again conquered by Soviet Union in 1945). During that time, Church and faith were one of the primary allowed (or at least tolerated by the occupants) expression of one's identity as a Pole - people were singing partiotic songs during masses, priests were leaders of the nationalist opposition (and frequently murdered for that) etc. Hence, historically Catholic Church means much more to Poles than to most other nations.
Nowadays though I would call it what it is - it's cancer growing unchecked on the Polish state. And I don't mean the religion - I mean the Catholic Church of Poland is constantly meddling in Politics, influencing new policies, Polish bishops are almost celebrities with a huge amount of wealth, the church does not pay taxes, they are one of the largest land owners in Poland....it's a frightening insitution that only seems to be growing in strength, you'd think young people would turn away from it, but with the current right-wing government literally saying that those who don't defend the church are not real Poles it's quite obvious what the party line is - either you are with the church or you are not welcome.