The similar phrase 'Worldly Christianity' is one used by Bonhoeffer. 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.
If you are wondering what has happened to these - it has been busy with visitors and this week some travelling and so a regular day off has not been possible. I'm not overworking, however, I'm sure. My main reason for writing about days off is to encourage younger men in the ministry to try to have a day off.