As a boy May was the big month for birthdays with me and my dad, my nana and several cousins having birthdays then. My sister was the only one in September. By now I have a wife, two sons, a nephew, a niece plus my oldest son's wedding anniversary as well. Dewi was first on the first.
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.