They convince themselves they don't believe in Satan and they are Atheists. This is the logic they follow according to Wikipedia. They are deceived. They WORSHIP Satan
Members do not believe that
Satan literally exists and do not worship him.
[3] Instead, Satan is viewed as a positive
archetype embracing the Hebrew root of the word "Satan" as "adversary", who represents
pride,
carnality, and
enlightenment, and of a
cosmos which Satanists perceive to be motivated by a "dark evolutionary force of
entropy that permeates all of nature and provides the drive for
survival and
propagation inherent in all living things".
[2] The Devil is embraced as a symbol of defiance against the
Abrahamic faiths which LaVey criticized for what he saw as the suppression of humanity's natural instincts. In his book,
The Satanic Bible, the Satanist's concept of a god is described as the Satanist's true "self"— a projection of his or her own personality, not an external deity.
[4] Satan is used as a representation of personal liberty and individualism.
[5
en.m.wikipedia.org