no no no no no no no and no. There are some very huge key differences between Satanism and Objectivism.
#1 Satanists preach the sacrifice of the weak for the strong as the antithesis of Christianity preaching sacrifice of the strong for the weak. Objectivism says there should be no sacrifice, period.
#2 Satanists view man as no better or different than a wild animal, Objectivists view man as a heroic being, who's ability to reason places us on a higher level than a mere animal.
#3 Satanists use rituals as a way to experience reality "in different forms", Objectivism states that there is only one reality, the one that we can view objectively (hence the name of the philosophy).
#4 Satanism says "do as thou wilt"... indulge in life's pleasures whenever you see fit. Objectivism tells you to indulge in life's pleasures but to do it rationally, not at the whim of the moment based on irrational emotions.
#5 Satanism says its ok to act on emotions rather than reason, Objectivism views this as irrational.
Both the satanic religion and the objectivist philosophy are based on individualism and atheism, but the similarities pretty much stop there.
The reasons why Objectivists are atheists are pretty straightforward... if the self is the strongest, highest power, you can't have some invisible man in the sky who's supposed to have some kind of infallible dominance over you. You're also never called upon to prove a negative. Believing in God is akin to believing in unicorns... there is no proof of either, and to believe in something that cannot be proven based solely on an emotional response is highly irrational.
I liked what a friend of mine said about agnostics... an agnostic is an atheist who doesn't have the balls to make up his mind