I went today to the Dulwich Picture Gallery. I'd never been to Dulwich before so that was a treat. Dulwich Picture Gallery is pretty unique, being the first public picture gallery ever. It is a small gallery but it has quite a collection of mostly 17th century paintings including a room of Poussins. Worth checking out. See 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.