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.
One of my sons famously thought novella was a posh word for a novel. It just refers to a short novel - about 150 pages or less. Here is a list of ten. These are ones I have actually read.
1. Bartleby the Scrivener Herman Melville 1853
2. The Strange Case of Dr Jekyll and Mr Hyde Robert Louis Stevenson 1885
3. Heart of Darkness Joseph Conrad 1899
4. Ethan Frome Edith Wharton 1911
5. Of Mice and Men John Steinbeck 1937
6. Animal Farm George Orwell 1945
7. The Old Man and the Sea Ernest Hemingway 1952
8. Breakfast at Tiffany's Truman Capote 1958
9. One Day in the Life of Ivan Denisovich Alexander Solzhenitsyn 1962
10. A Month in the Country J L Carr 1960