Earlier this evening we listened to my friend Alan Davey on helping our missionaries. He began with the Apostle Paul and moved on to Adoniram Judson to some modern examples of missionaries in tight spots. His focus was on how we can help such people. Suggestions included recognising that there is a price for them to pay and the need for us to prepare them and pray for them. Visits and sending helpful things can also be a help but we need to let them make their sacrifice.
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.