The conference continued yesterday with an excellent overview of Revelation 20 by Reformed giant Joel Beeke and then in the evening a look at Isaiah with the distinctive (and slightly taller) Mike Reeves. I heard them both in the afternoon, along with Bill Bygroves, very usefully looking at the subject of evangelism.
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.