In late 1995 I stole a copy of "The Secret Life of a Satanist" by Blanche Barton1 from a suspecting friend. I read through it and suddenly found myself in the unexpected position of agreeing with Satanism. I didn't tell anyone about it for a few years, but used it as an internal source of inspiration. After that, I became a card carrying member of the COS and went through all LaVey's books.
Satan is a personification for the driving force in life: it is darkness, the inevitability of death that encourages me to live life fully whilst I'm still alive! So... Satan *is* what I love in life... in particular at this time Satan is: Love, affection, music, large cities, computers and self empowerment. Satan is the personification of intelligence and rebellion; enlightenment, happiness and indulgence. But purely a symbol, and not a reality.
Satan represents darkness, ultimate death, ultimate hopelessness, the existential void, loss, decay and entropy. These things, hanging over your head, serve only to make life more urgent. I must live for as long as possible, because reality does definitely not give a shit about me! So Satan is muse for me to take long term plans, not to get myself killed, not to neglect my mental or physical health. Satan represents these things and forces me to make my life productive.
Satanism has at its core a solid atheist philosophy.
Ludicrous bad example of a religion
Before I became a Satanist I didn't know much about religion or religions.... I had no religious relatives, my schooling was completely secular, with the exception of a few lessons on world religions (which concentrated on dates, holidays, founders and terminology).
But when I discovered Satanism I realized that it had potential to attack all religions through its nature. By being viewed by many as completely ludicrous, yet also by being a valid religion, it could have the effect of making people reject religion and superstition more readily. People are fed up with religion... making Satanism higher profile will be another nail in the coffin of God(s) and religion!