Cuilidh (the word means place of retreat) was Julie Fowlis's second album and came out in 2007. It features several songs in Gaelic (one acapella) and some instrumentals and not a word of English! Everything is played on traditional folk ounding instruments (though the piano also gets a look in). The two singles from it were "Turas san Lochmor" (all about sea travel apparently) and the delightful "Hùg Air A' Bhonaid Mhòir" (celebrate the big bonnet) which is Puirt a beul or Mouth Music (other such items occur - on one of them it sounds just like she's saying Barry Manilow. In Oran nan Raiders I can hear the name Lloyd George!). Another favourite of mine is "An t-Aparan Goirid 's an t-Aparan Ur: Oran do Sheasaidh Bhaile Raghnaill". 4."'Ille Dhuinn, 's toiigh Leam Thu" is also vey 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.