The similar phrase 'Worldly Christianity' is one used by Bonhoeffer. 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.

My Testimony

[Pics: I used to sit in the third pew on the right; the room where I was converted then just had bare floorboards; idyllic looking the 1836 building is now surrounded by a housing estate]
My parents were not Christians but they were moral people and they brought me up in line with the Ten Commandments, including the idea that Sunday is special and that I ought to go to Sunday School. I never got on with Sunday School as a child but I did start attending the Friday night meetings for young people and the Sunday evening service when I was 11 or 12. Then one night I was converted.
It was the early seventies so my hair would have been touching the panda collar of my Ben Sherman shirt. I would have worn flares and stack heel lace-ups and possibly a tank top knitted by my mum. It was a long time ago! After a sausage and chips meal, we sat and listened to the visiting speaker.
It was Spring time and I remember sneezing a lot with hay fever but I was still gripped. I don't recall very much about what the speaker actually said though I'm sure he urged us all to trust in the Lord Jesus. Afterwards he gave us something to read and the minister of the church urged me to look at John 3, which I probably did. I certainly prayed, confessing what a rotten sinner I was and asking that I might be born again. I don't remember church the day after next but certainly the matter was still on my mind when I headed for school the following Monday. I was determined to let others know that I was now trusting in Christ.
Not being from a Christian home this change was quite a dramatic one in some ways. Just over a year later I was baptised by immersion at the same chapel where I had been converted. From early on I felt called to be a preacher.
About 10 years on, after time away studying in Aberystwyth University and London Theological Seminary, I became a minister. I am still not what I would call a religious person, although I obviously pray and go to church. What I'm trusting in is not my religion but the grace of God in Jesus Christ my Saviour.