General indications are that the US is more than twice as religious as anywhere in Europe (Poland might be highest, catholic countries seem to have mpst persistence of religion). We are atheist, muslim, or generally not bothered.
Poland is not the highest for belief in God. They are bested by Malta (94%), Croatia (93%), Romania (92%), Cypress (88%), and tied with Greece (79%). Others above 50% are Italy (74%), Ireland (70%), Portugal (70%), Slovakia (63%), and Spain (59%).
Germany is at 44%, the UK at 37%, France at 27%, and Sweden at 18%.
Note the above is belief in a God. When you add in the spirit or life force belief, some of the countries shoot way up. Sweden is only 18% belief in God, but 45% spirit/life force, with only 34% not believing any of that.
That still leaves Sweden with the third highest unbelief, behind the Czech Republic (37%) and France (40%). Germany is 27% unbelief and UK is 25%.
[1] http://en.wikipedia.org/wiki/Religion_in_the_European_Union
I don't think the majority of Poles are actively "Catholic" in their religious metaphysical beliefs, but rather they all belong to the church because of its cultural importance. I could be wrong, however, as I don't live there.
It makes me wonder about other countries where the church plays an important cultural role (Italy, for example.)