We were in Matthew 3 (Jesus's baptism) and Esther (6) again yesterday. Numbers were down rather especially in the evening for some reason. The sermons were quite a contrast. I found it a little difficult to find my way preaching on the baptism of Jesus for some reason and the sermon came out relatively short (under 30 minutes). I found Esther 6 much easier and it was approaching 40 minutes by the time I had finished. I tried to be evangelistic in both - and hopefully did that. Praying was much more difficult than preaching for some reason.
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.