Lincoln biscuits remind me of my Nana Pidge, my dad's mother, partly because she would serve them but chiefly because in a drawer in her kitchen there was a trick one. It looked like a Lincoln biscuit from one side but then you turned it over and there was a mirror on the other side. I don't think I ever genuinely caught anyone out with it but the very idea thrilled me.
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.