Another good candidate may be revealed in the following Dostoevsky quote:
“If someone were to prove to me that Christ is outside of the truth, and it were truly so, that the truth was outside of Christ, I would prefer to remain with Christ, rather than with the truth.”
Substitute ‘Christ’ for your favourite deity/belief system. This was the epistemological line I was not able to cross during my christian journey. Others may however, and once it is crossed, there may be little that can be done to rescue that person (other than perhaps pure shock and awe at the reprecussions of such a departure from reality). If this is not the root of a ‘dark side epistemology’, it is certainly the pinnacle of it, the final lie that must be accepted to justify all the ones that came before it.