Since The Church of Satan is an Atheistic Institution, Why is Solipsism a Cardinal Sin?

My theory:

Everything in totality may or may not exist; it may be an illusion; a figment of what reality truly lies ahead. Many individuals and populations as a whole remain unaware of what amalgamates the psyche and the environment in which they dwell, resulting in a providence of untenable conception of what and how concepts should be constructed in a productive manner. Therefore, by understanding that reality is but a mere concept, no more pragmatic than any tangible object, it is then that an individual or a population may establish arbitrary concepts relative to their overall productivity in a realm where existence is epistemological as it is emblematic in nature. This is highly essential due to the fact that arbitration is dictated by limits and the disruption of nature as an evolutionary product. Instead, concepts become nothing more than the reality it is subjected to, which is one of uncertain constructs. It is the transcendental realm and the aftermath of a blinded population unable or unwilling to accept individual arbitrary composite objects. And like all cult leaders, Anton LaVey was no different---utilizing facets of menticide to recruit and retain followers.