Too abstract, too subtle, easy to miss now, when most people are unfamiliar with the metaphorical allusions that people in the early 20th century took for granted. Ultimately, he could not stem the post-Christian rot that has infected the West for the past 150 years.
Well, I didn’t miss it. :)
You do have to have some familiarity with Christianity to catch themes. Otherwise, to the unfamiliar secularist, it’s just a deep book with some good lessons when analyzed.