The similar phrase 'Worldly Christianity' is one used by Bonhoeffer. It's J Gresham Machen that I want to line up most closely with. See his Christianity and culturehere. 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.
Latest Edition of In Writing now out
Edition 138 of In Writing is now available from the Evangelical Library.
I notice I have credited myself with the article The Nightingale of Wittenberg which is incorrect.
It was the work of Dr Ian Densham. Sorry Dr Densham.