Today is my mother's birthday. She's not celebrating - well, no more than she does every day if she's gone where I think she's gone. She would have been 81 if she'd hung around which (as they say) is not old these days. I still miss her ever day, even though she died 16 years ago. God knows best.
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.