[Pearl] Zane Grey (1872–1939) was another American author best known for his popular adventure novels and stories that were a basis for the Western genre in literature and the arts; he idealised the American frontier. Riders of the Purple Sage (1912) was his best-selling book. In addition to the commercial success of his printed works, they had second lives and continuing influence when adapted as films and television productions. As of 2012, 112 films, two TV episodes, and a TV series (Dick Powell's Zane Grey Theater) had been made that were based loosely on Grey's novels and short stories. Wikipedia lists over 90 of his books mostly westerns. He was one of the first millionaire authors.
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.