You don't have to apologize to me - you're certainly entitled to your opinion. I disagree with you, though given the circumstances that certainly isn't unexpected.
Please bear in mind that the Temple of Thelema (where I assume you found the quote) is one of several Thelemic groups, and do not necessarily speak for everyone. Still I am genuinely curious as to what you find offensive about that particular statement. If you take the Great Work as the perfection of the individual (which I do) I don't see what could possibly be wrong with that.
If you really think that Thelema is designed to 'erode the reason and instill faith' you are mistaken, but you can't be faulted for thinking that for a brief internet search. Any philosophy is complex, and the things that you're most likely to see first are the more sensational aspects, and those do appear superstitious.
As far as justification for my epistemology I didn't offer that because it doesn't exist. Thelema is not the basis of my epistemology, my experience is. Thelema is how I describe and relate to that experience.
In any case, I don't really hope to or desire to convince you - that's not particularly important. Just hoped to express myself a little more clearly, have some dialogue, and try to understand what you find offensive about the quote.