It was a proud moment to be (for the first time I confess) at the new building of Yr Ysgol Gymraeg Llundain, the school all my children attended and for which my wife is chairman of governors. The first minister of Wales, Carwyn Jones, was there to do the honours and the children sang beautifully. The building is light and airy and an ideal spot. Good day.
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.