Major part of citizens are simple, not-educated idiots, but atheists don't mind them and over 50% of people who declare to be catholics don't practise, so they are almost-atheists. Generally polish nation is conservative and declares to be religious
They don't care about atheists, maybe only elders living in villages don't like them too much. Most people's opinion about Satanism isnt good, because they think it's about literal worshipping Satan, black masses etc.
It's rather old question, but I thought that I may add something since I'm atheist. Usually people don't care, at least the ones with some brain. Several times I've heard that I'm immoral because I don't believe (which is pretty funny considering the fact that I had asked the person who told me that to stop calling our friend "failure" all the time because it isn't nice). I guess it's pretty easy to guess what probably most nuns and priests think - that I'll go to hell, no matter what. It's to be expected. For agnostics, I heard once from a priest that they secretly believe in God and their whole "I don't know" proofs that he exists... Because they know deep down in their heart. Though I wouldn't really care about this person's opinion - he once said "If one day you decide to be introvert", which is... Well. Anyways, he treated introversion like a disease. All in all, I'd say that it really depends on people you are surrounded by. My environment is rather religious, so I'd rather be quiet about being atheists. (Sometimes during Polish classes I've heard some comments about atheists and I think it may not be the best idea to come out as one). I'm not saying all religious people are bad either though - some even think I'm brave. For satanism, most people don't know what it is, especially older ones, so they focus on the name. "Satan-ism?"=probably something to do with satan. So they may think it's evil and that's all. In both cases, older people probably are more opinionated (and ignorant) than younger generations.