The current Lord Mayor of London is a Welsh man and as it is the fiftieth anniversary of Ysgol Cymraeg Llundain where my younger boys attend he kindly arranged a celebration there last night. The event was covered by the Welsh language proramme Wedi saith and if you go to the site(http://www.s4c.co.uk/e_watch_wedi7.shtml) at the moment you can see a package on the event (Wednesday c 1:50-9:30) including a brief interview with one of my sons (all in Welsh of course). The rest of the family went but I was not able to be there as it was prayer meeting night and I wasn't organised enough to rearrange things. The video shows Gwion's speech. You can spot Owain third from the right in the choir.
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.