To quote Herbert himself, from an unpublished 1978 interview with Tim O’Reilly, he used this vocabulary, partly derived from “colloquial Arabic”, to signal to the reader that they are “not here and now, but that something of here and now has been carried to that faraway place and time”. Language, he remarks, “is mind-shaping as well as used by mind”, mediating our experience of place and time. And he uses the language of Dune to show how, 20,000 years in the future, when all religion and language has fundamentally changed, there are still threads of continuity with the Arabic and Islam of our world because they are inextricable from humanity’s past, present, and future.

A quick look at Frank Herbert’s appendix to Dune, “the Religion of Dune”, reveals that of the “ten ancient teachings”, half are overtly Islamic. And outside of the religious realm, he filled the terminology of Dune’s universe with words related to Islamic sovereignty. The Emperors are called “Padishahs”, from Persian, their audience chamber is called the “selamlik”, Turkish for the Ottoman court’s reception hall and their troops have titles with Turco-Persian or Arabic roots, such as “Sardaukar”, “caid”, and “bashar”. Herbert’s future is one where “Islam” is not a separate unchanging element belonging to the past, but a part of the future universe at every level. The world of Dune cannot be separated from its language, and as reactions on Twitter have shown, the absence of that language in the movie’s promotional material is a disappointment. Even jihad, a complex, foundational principle of Herbert’s universe, is flattened – and Christianised – to crusade.

One can understand why. Even before the War on Terror, jihad was what the bad guys do. Yet as Herbert understood, the term is a complicated one in the Muslim tradition; at root, it means to struggle or exert oneself. It can take many forms: internally against one’s own evil, externally against oppression, or even intellectually in the search for beneficial knowledge. And in the 14 centuries of Islam’s history, like any aspect of human history, the term jihad has been used and abused. Having studied Frank Herbert’s notes and papers in the archives of California State University, Fullerton, I have found that Herbert’s understanding of Islam, jihad, and humanity’s future is much more complex than that of his interpreters. His use of jihad grapples with this complicated tradition, both as a power to fight against the odds (whether against sentient AI or against the Empire itself), but also something that defies any attempt at control.

from https://www.aljazeera.com/opinions/2020/10/11/paul-atreides-led-a-jihad-not-a-crusade-heres-why-that-matters

Sufi scholar talking about herbert's understanding of Islam and how that is reflected in the work.