In one sense, the explanation for the so-called 'demise' of Christian education is very simple. Once, "Christian education" was the 'umbrella' term for both formation and education. Now, "formation" is becoming the "catch-all" to describe both formal and informal nurture/socialisation and education.Is this a good thing or a bad thing, or doesn't it really matter?
As I mentioned previiously, the development of CE in the USA paralleled the development of 'secular' education during the 20th century, with the former taking many cues from the latter (This is somewhat different from when the church was the leader in education in earlier times.) What this resulted in was both CE roles (paid and unpaid) in congregations, and courses of study in CE in universities and seminaries. Each fed the other, and fuelled the commitment of churches to lifelong Christian learning.