It was a great privilege to be the speaker at Feltham Bible Focus last Saturday on Keep yourselves from idols (the message will appear on the Feltham website eventually). I had a lovely meal beforehand with the pastor of Feltham Evangelical Church Phil Venables and his family (like us it's all boys, home schooled but also learning Chinese, part of their maternal heritage). About 40 gathered mostly from the Feltham church but also from other churches nearby. There was a good age spread and a happy atmosphere. Refreshments were served after. What a good evening.
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.