The C S Lewis Chronicles by Lewis expert Colin Duriez is a slightly strange volume in that it is not a straight biography but a chronicle covering the years 1862 (when Lewis's mother was born) to 1998 (when centenary conferneces were held in Lewis's honour). This era is split into eight eras headed 1898-1908, 1909-1916, 1917-1918, 1919-1925, 1926-1938, 1939-1945, 1946-1953, 1954-1963. Each chapter has an introductary summary and the various date headings with information beneath. There are also a series of extra sections covering important people in Lewis's childhood, Narnia and the north of Ireland, important childhood places, Top Ten Books, The Four Loves, etc, etc, etc. Some will find the annual reference to the passing of Lewis's birthday on November 29 tefious but I found it a help. This is not the place to begin to read about Lewis but if you have some ideas about him this is a good way of learning about him and his circle. I borrowed my copy from the Evangelical Library.
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.