William Thomson, 1st Baron Kelvin (1824 – 1907) was a Belfast-born mathematical physicist and engineer. At Glasgow University he did important work in the mathematical analysis of electricity and formulation of the first and second laws of thermodynamics, etc. He also had a career as an electric telegraph engineer and inventor, which propelled him into the public eye and ensured his wealth, fame and honour. He was also noted for his work on the mariner's compass. He is widely known for determining the correct value of absolute zero as approximately -273.15 Celsius. Absolute temperatures are stated in units of kelvin in his honour. He was the first UK scientist to be elevated to the House of Lords. He remained a devout believer all his life, a member of the Church of Scotland. He saw his Christian faith as supporting and informing his scientific work, as is evident from his address to the annual meeting of the Christian Evidence Society given in 1889.
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.