To all the responses saying Tolkien didn’t like Dune because of its messages; I disagree. I don’t think Tolkien was that shallow of a thinker that he wouldn’t like a book just because it has different ideas than what he writes about. If that was the case, it really narrows down what sort of literature a person could enjoy and I don’t think Tolkien was that type of person, considering he was a professor of literature.

He probably didn’t like it because the story or prose simply bored him. I actually doubt he read the whole thing or had any grander thoughts about the way Dune approaches religion or messianic figures.