If you have problems opening itunes in Windows 10 try right clicking on your iTunes icon and choosing "troubleshoot compatibility". Work through the menu then choosing "troubleshoot program" and "don't know" (for which version of windows?). It worked for me.
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.