In Christian Satanism the Devil exists and is being worshipped. This is “classical” or “theist” Satanism where there is a belief in the existence of Satan.
Contrast that with modern atheist Satanism, where the Devil is merely a psychological symbol of rebellion, independence and freedom that serves to trigger theists while also being a representation of revolting against christan authoritarianism and, through the exploitation of rules stemming from theist-political decisionmaking, as a counter to the blatantly unconstitutional abuse of religious freedom laws for the benefit of a single religion.
The Satanic Bible is LaVeyan Satanism and as a product of the 20th century very much more modern than the “traditional Satanism” of de Sade and Huysman in the 19th century.
LaVeyan Satanism is still much more on the “spiritual” side of things than, for example the explicitly atheistic, sceptic and rational Satanic Temple, but both fall under the umbrella of the more modern, non-theistic understanding of Satanism. While a more historical form definetly existed, even if it wasn’t widely practiced.