I finished reading The Riddle of the Sands by Erskine Childers the other day. I picked it up and put it down several times in recent years but have finally finished it. It is a spy story in the style of a John Buchan novel I suppose. Such books are easier to watch as films than to read. The book uses a large number of nautical terms and so I had to look up several terms. I read most of it ona kindle, which comes into its own in that situation as it is a simple matter of highlighting the word and reading the dictionary definition. The yarn is a good one adn worthy of its reputation. I seemed unable to find a copy with maps, which is a helpful extra in trying to follow the plot.
Bonhoeffer uses a similar phrase 'worldly Christianity'. It's J Gresham Machen that I want to line up most closely with. See his Christianity and culture here. Having done commentaries on Proverbs (Heavenly Wisdom) and Song of Songs (Heavenly Love), a matching title for Ecclesiastes would be Heavenly Worldliness. For my stance on worldliness, see 3 posts here.