I found Ross Douthat's comments quite germane:
...the Victorian project (which persists to this day) of doing away with Christian dogma but trying to keep Christian morality intact is doomed to failure. Not because Christian morality can’t be approached rationally by nonbelievers of good will, but because without the lived experience of a religious tradition it will never be anything more than an abstraction, an arid intellectualism, something that gets followed when following it is easy to follow and abandoned as soon as the going gets tough.
If we lived in the 15th or 16th century, secularism would provide the necessary corrective to the certainties of religion.
I'm really not sure that period can be rightly described as secular. As I read it, the aftermath of the Reformation led to the rise of divine-right monarchy, then later to the pseudo-religion of nationalism.
Yet I am pretty sure that the kind of skeptical examination of self and society on display here was nurtured in a Christian culture. I doubt that it will survive intact should that culture be significantly compromised, as is happening today.
Naw, mine comes from Buddhism. When I was Christian, I was taught that some things should not be examined.
That argument is irrelevant because the simple fact is that belief does not prevent morality from being abandoned when the going gets tough. If anything, it leads to morality being debased into a justification for evil, which turns out to be worse than simple abandonment.
For example, it was "tough" to stick to "Thou shalt not covet", "Thou shalt not steal", and "Thou shalt not kill" when applied to the local Jewish moneylender. Voila -- a "Christian" justification for reneging on debts and running out or killing the creditor was readily found.