Monday seems a long time ago now but back then we had a lunch time lecture from Robert Strivens on the Puritan William Perkins. We had a good turn out and Robert helpfully took us through Perkins' relatively short life and introduced his works to us. Joel Beeke's RHB imprint has just published the first of a projected 10 volumes of Perkins' works. I've sent for my copy from ICM. This looks like a worthwhile project.
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.