"The diabolical works by leaching energy from reality but pointing to itself as the final authority. It is primarily negative—a verneinender Geist, as Goethe wrote in Faust, that defines itself through its opposition. It 'mimics, rather than mediates' reality, obsessing over appearance while simultaneously functionalizing reality. It presents itself as somehow better than the real, and it partitions people inside of their own subjectivity. And it acts as a 'translation of eternity into its possibilistic, horizontally contained, image: it is not a self-transcendence, but a constant repetition of the self into a future without meaningful limit, or in other words without the limit of meaning.'”When I first read this, language like, "its possibilistic, horizontally contained, image", sailed over my head, and I suspect most of my readers will have a similar experience. In fact, there is something diabolical in that style of writing, The key point that I do understand is that the diabolical "presents itself as somehow better than the real", and that is how Satan works. Revisionist priests and bishops typically present their interpretations of the Gospel as somehow being better than what a plain reading of the Bible provides to the simple pewsitter, and revisionist teachings can easily mutate and reappear in new forms because they are not restrained by the limits contained in scripture.
The diabolical is real, and when asked to define it, most of us would struggle to find the right words to use. Recognizing the diabolical can be a struggle too, but when you can detect that an idea or teaching will eventually lead to a denial of God or his revelation in the life, death, and resurrection of Jesus, then you know that you are in the presence of the diabolical.