So at last it's here. I had to read it through to see what it was like and if there were any mistakes. I spotted no typos but there are one or two minor 'continuity errors'. I hope it will be a help to young Christians and serioous unbelievers who want to explore the subject. What a privilege to be involved in such a project. Do check it out. I think it goes for around 7.99.
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.