I recently saw on Netflix the film The Polka King starring Jack Black. Black is a brilliant comic actor and he is excellent in this biopic based on the life of a Polish immigrant to the USA called Jan Lewan(Dowski). Like The Wizard of lies (Starring Robert de Niro) the film presents a character who engages ina Pnzi scheme that eventually unravels and leads to a prison sentence. The previous one is full of swearing and other unhelpful material, sadly, but this one is a lot more user friendly. In both cases, we see a charming man full of good intentions but just below the surface an evil willingness to deceive.
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.