I was walking along the Kilburn High Road when a man from South India asked me if I would like a palm reading. I told him I didn't and that I didn't believe that such things were true although no doubt he was a very good reader of people and could tell me things about myself that others may not be able to. So as a test I asked him to guess my age. He looked at me for a moment and said 54. Spot on! My point is that he didn't get that from looking at my palm but just being a discerning fellow with a gift from God. I suppose the difficulty is how you make money out of telling people their age.
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.