Joseph Conrad (Józef Teodor Konrad Korzeniowski 1857 – 1924) Born in Russia and dying in England, Conrad was a Polish author who wrote in English. Granted British nationality in 1886, he always considered himself a Pole. He is regarded as one of the greatest novelists in English, though he did not speak the language fluently until he was in his twenties (and always with a marked accent). He wrote stories and novels, often with a nautical setting, that depict trials of the human spirit in the midst of an indifferent universe. He was a master prose stylist who they say brought a distinctly non-English tragic sensibility into English literature. His modernist style influenced many. Films have been adapted from, or inspired by, his An Outcast of the Islands, Heart of Darkness, Lord Jim, Nostromo, The Secret Agent, The Duel, Victory, etc, etc. I have only read the novella Heart of darkness I must confess.
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.