I find ecological aspect of 'Dune' very compelling. It is one of the major themes of the book, but rarely mentioned in any overview videos. All life revolves around water (or rather absence of it) preservation of water (water is even reclaimed from your breath) all life forms on Arrakis are evolved to adapt to these harsh conditions. I can say that water is the second axis of the book, first one being spice melange. Both of these axes intersect at a single point - to make spice melange you need water as well. In terms of Christianity (blood of the Christ and eating Eucharist) water can be compared to blood and spice to Eucharist. Eucharist even having some more ancient roots to consumption of psychedelic materials to reach higher states of consciousness (like some mushroom caps consumed by ancient societies) but this is whole new topic for another day. Another aspect is religion. You can literally find various aspects of all current major religions, main ones being islam+zen Buddhism. The more you are acquainted with various religions the more details you recognize in the book. Also eugenics motif is very strong with Bene Geserit breeding program, trying to breed 'super-human' over the thousands of generations from selected gene-pools and traits. Including very strict conditioning of each Bene Geserit woman, being like a vessel to produce 'all seeing, all knowing' human.