I discovered this song through my sons. Called unbelievers it is by Americans Vampire Weekend. Still not sure what the lyrics, which talk about being born again and hell and sinners, are saying but certainly this is what many unbelievers are like - young, handsome, artistic, clever and asking questions. They are clearly not excited (indeed desperate not to be) even though they should be.
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.