I'm not a huge rugby fan but being Welsh you can't ignore the Six Nations tournament which starts Feb 03. I understand that the filming my son did with Jeremy Guscott and Brian Moore the other day will feature in the Grandstand programmes in connection with the various games. There is a nice site where the two explain a bit about rugby here.
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.