Great article. I love both author's as well.
Tolkien was a devout Catholic who even argued theology with the likes of C.S. Lewis. You can make a fair assumption that the presence of Islam in the far future and no Christianity was part of his personal distaste, in my opinion.
Herbert's works have a certain pragmatism and prophetic believability that Tolkien's beautiful fairy tales fall short of. And Herbert makes me ponder far more. I particularly found Heretics of Dune, which I read in my late teens to be philosophically engaging, and what I thought to be Herbert's genius on par with Socrates and Plato when I read them in college a year later. I'll have to revisit it to see if I still hold the same opinion. Regardless the author holds a special place in my heart and mind.
Thanks for this piece!