Satanism as a magical or religious art focusses primarily on one question: Why are we here? This site being about magic, not religion (though it does occasionally impose itself into the magical framework, and mostly so in the art of Satanic magic), I will ignore the various religious answers and move straight to the magical philosophy behind that question. Pop culture indicates one of two answers to the reason of our existence:
1. We are solely for the purpose of worshipping God the Creator, or some grand entity therelike, and to base our existence around pleasing this cosmic entity by following rules of conduct and morality.
2. We are here because of a big explosion which was followed by gradient evolution, relying on a chemical soup of unknown composition and mere chance to cause sequence after sequence of minor change over a span of millions of years to produce everything now seen. Therefore the supernatural is either non-existant, or doesn't play a part in life.
This only presents two options: Poof or Bang. To a Satanic Magician, both of these options are unusable. If the first is true, then we are here only for worship to an omnipotent entity who shows no physical manifestation on earth. The Satanist poses the question "Why doesn't God speak with a thunderous voice any more? Why, if He exists, does He not prove His existence anymore with loud speeches and fire from Heaven? Where is the concrete, easily found and undeniable proof?" The second option is unusable as well. If random energy were to cause order in the universe, why does entropy exist? The Laws of Thermodynamics (and particularly entropy) prohibit the possibility of the theory of evolution from being true, as is becoming more and more apparent in scientific circles (especially in the different sub-disciplines of physics).
So, now having discluded the two major views of origin, one wonders where the Satanist stands on this subject. The answer is "in the centre of everything". Satanic magic is focussed on the worship and building up of your own soul as unto the potential of a major deity. Every person, in the Satanic view, is a god unto themselves and an eternal being of equal potential power to that of any existing entity. The Satanic Magician may or may not, in this view, believe in Satan or other demons, and may not even pay heed to the existence of any kind of spirit at all. The important part of any mystic operation, to the Satanist, is the accumulation of basic terrestrial power and using this energy to manifest itself in a tangible and usable format in the visible mundane world. Instead of seeking power from the external world or planes, the search continues on an intrapersonal level, or perhaps with terrestrial entities (such as minor demons). This is the contrast between Celestial magics and Satanic magics, one seeks aid from the outside, and another from the person.
Mainly, Satanism only really revolves on certain types of spells, usually only 3 accually. These are spells of lust, compassion and destruction. Their magical methods include only spells which bring satisfaction to themself through the use of infernal and/or Satanic powers.