I enjoyed watching a documentary on Buddy Holly recently. See here. I had never seen this 1955 pic of Elvis when he came to Lubbock. You can see Buddy Holl(e)y (and Bob Montgomery) in the picture. Apparently, it was after hearing Elvis that Buddy began playing rock 'n' roll.
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.