We had our last bit of Christmas last Saturday. It wasn't possible to see my sister and her kids last year so we pencilled in a later celebration for January 16. We had a lovely meal together and swapped presents and played a game or two. Good fun, even if so late. We were fifteen altogether with the new baby and two of my boys coming back with their girl friends. Only one of my sister's kids couldn't make it. I managed to get crackers online through Tesco, not that they were very good.
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.