William Somerset Maugham (1874 – 1965) was a British playwright, novelist and short story writer. He was among the most popular writers of his era and reputedly the highest paid author during the 1930s. After losing both his parents by the age of 10, Maugham was raised by a paternal uncle who was emotionally cold. Not wanting to become a lawyer like other men in his family, Maugham eventually trained and qualified as a medical doctor. The first run of his first novel, Liza of Lambeth (1897), sold out so rapidly that Maugham gave up medicine to write full-time. During World War I, he served with the Red Cross and in the ambulance corps, before being recruited in 1916 into Secret Intelligence, working in Switzerland and Russia before the October Revolution of 1917. During and after the war, he travelled in India and Southeast Asia; all of these experiences were reflected in later short stories and novels. He wrote many novels including Ashenden: Or the British Agent, Cakes and Ale, Catalina, The Magician, The Moon and Sixpence, Mrs Craddock, Of Human Bondage, The Painted Veil, The Razor's Edge, Then and Now and Up at the Villa. I've not read any of them.
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.