This is my personal opinion as a Satanist.
What is a Satanist? A person.
What is Satanism? For me a way of life, a philosophy.
Satan: Hebrew, meaning advesary or the accuser.
Ist: meaning the I AM or What I am.
Total meaning, A person that identifies him/her self with Satan. Satanism: Is the philosopy of a Satanist.
Satanism is a personal and very independent spiritual path.
It is NOT for the masses.
Anton Lavey, whom I consider to be the Godfather of modern Satanism wrote the Satanic Bible. I find it to be a blueprint for worldly conduct and fleshly idealism but I feel it holds no true spiritual substance. As they do not believe Satan to be a living entity. This is where the different paths of Satanism come into play. My personal belief is that this is a individual, independent, sometimes spiritual, religious philosophy that worships Satan as God. In short, I will end by saying, if this spiritual path is for you, YOU WILL KNOW.
Always keep in mind that developement to spiritual consciousness and individual spiritual power is the main goal of every spiritual path.