Well, the Polish are definitely sensitive about religion. I think most of us knew that. But Behemoth singer Nergal apparently knows this first hand now. In Poland, offending someone based on their religion is a criminal act. Nergal is a very outspoken critic against Christianity, and Catholicism in particular. In a concert in 2007, he called the church "the most murderous cult on the planet" and then proceeded to tear apart a Bible onstage. Ryszard Nowak, Head of the All-Polish Committe for Defense Against Sects was not amused and tried to sue Nergal soon after. This was unsuccessful however as there have to be multiple complaints to bring the action under Polish law. Undaunted, he found some other willing people to help him out.
Nergal's stance is that he has artistic license to do what he wants as it is entertainment when he is onstage and no one should be offended.
I do not know anything about Polish law to be able to comment on what should or will happen in this case. I know this would be considered Free Speech in the U.S. and would be subject to the First Amendment. But Poland does not have the same rules and laws as the U.S. At any rate, this is more fuel for the fire of hatred Nergal feels towards Christianity.