I can be quite slow on the uptake at times but I noticed in The Times recently that Harry Blamires has died (it was actually over a month ago now). I remember hearing his book on The Christian mind being commended and buying a copy. I must admit I never did get round to reading it. His Wikipedia page here shows what an interesting fellow he was.
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.