Following his message at the recent Grace Assembly, Stephen Rees's comparison of the 1689 Confession and the 1966 Affirmation is now available in pdf form here on the Assembly website.
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.