The 6.30 pm BBC TV News devoted the whole of its programme to the death of Muhammad Ali. If you weren't around in the sixties you may not realise how big Ali was. This video may give you an idea.
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.