Why does everyone say that Satanism is very different from all other religions?

I am a Christian and I am not trying to insult anyone, but I am curious to find out more. I hear that Satanism is based on the physical realm and not the spiritual world at all which would make it different from other religions like Christianity, Paganism, Wicca, etc. So I guess I answered my own question, but is there more to it than that?

There are many forms of Satanism. All the ones I have encountered have mystical elements even the atheistic ones. So I am not sure what you are talking about.

There are two real types of Satanism: LaVeyan Satanism, which is an atheistic belief system. And Spiritual Satanism, which for lack of a better term is literal Devil worship.

LaVeyan Satanism-
http://www.churchofsatan.com
http://en.wikipedia.org/wiki/LaVeyan_Satanism

Spiritual Satanism-
http://www.joyofsatan.org
http://en.wikipedia.org/wiki/Theistic_Satanism

True Satanism puts spiritual power in the hands of the common person. This is a big threat to the enemy agenda of enslaving the populace so that the Chosen few have all power and the masses are powerless. Satan wants us to advance and live freely. Most other religions are based on restrictions and have elements in them that degrade the human soul. This is the difference. Satanism is about life, liberty, freedom, power, and the spiritual, and scientific advancement of humanity. True Satanism is about finding and celebrating humanities original religion. Also true Satanism, and Science go hand in hand.