WHY DO WE HAVE PANCAKES ON SHROVE TUESDAY? This day was formerly one of universal merrymaking and all kinds of amusements, being the last day before the start of the austerities of Lent. In Roman Catholic countries it is still a day of carnival. After having made confession, or shrift (whence 'Shrove') in preparation for the morrow, the faithful are allowed a brief interval of feasting, of which they take full advantage. As eggs and fats are forbidden during Lent, it is customary to use them up on Shrove Tuesday in fritters and pancakes, which thus become particularly associated with this day. The French call it "Mardi Gras," (Fat Tuesday) because of the fat oxen led in procession through the streets.
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.