Nothing. Hedonism, personal accountability and enlightened self-interest actually make a lot of sense. The problem is people equate it with "worship ping Satan", which just shows their ignorance of what LaVey wrote.
EDIT: Christians answering the question, Satanists DO NOT worship Satan.
"When one doubt is followed by another, the bubble, grown large from long accumulated fallacies, threatens to burst." (The Book of Lucifer)
The only things I see wrong with it come from my political stance; that satanism is more for libertarian capitalists, an ideology I'm opposed to.
That's LaVeyan Satanism anyway... Spiritual Satanism, just seems like a picaresqueQueligion to me, like wicca or neodruidry or asatru.
That's easy Satanists are worshiping a being full of extreme rage, pride, deep wickedness who wants to enslave the human race he wants to force every single man woman and child on earth to turn their back on God and take his mark (It's a microchip implant placed between your thumb) and worship him.
He has a letter for everyone to read by the way thanking you all for letting him use you:
Not a thing. It makes sense...as much as any religion does. The reason society thinks its wrong is because they know nothing about it. Period. All they get is one story, they never stop to consider there might be other views that are worth paying attention to.
The LaVey philosophy of satanism is a very 'SELF' oriented religion which is currently practiced by nearly the WHOLE WORLD and you can clearly see how well that is going.
I'd almost call Lavey-an satanism a "magical humanism." They don't really believe in a god or Satan, but by embracing the so-called 7 deadly sins, it kind of flies in the face of Christianity, so it's only satanism in that it's anti-christian. The philosophy is OK, I guess. The modified golden rule is interesting, do unto others as they do unto you. I start to really have a problem when they get in the ritual magic. I understand the concept, but it's still one of those supernatural things I have to back away from.
The most I've seen from Satanism is from the Satanic Bible by LeVay. I went in an atheist and came out an atheist.
LeVay chose the term Satanism precisely to filter out the people who couldn't get past the name. You've seen in other answers that it worked. For the most part, I didn't think what he was saying was so bad. Christians might be turned off by the whole sexual liberation deal. The reason I rejected it was that he suggested that humans need a religion and, ergo, Satanism would suffice. I don't feel the need for religion, so I'm not buying.