I do think Progressive like memes would have developed in a non-Christian descended implementation of what is often called The Cathedral
I think this is quite likely to be the case, since Progressivism (which one might think of as "altruism gone rampant") might actually emerge in time from the mating patterns and the resulting genetic structure of a population.
hbd* chick has built a compelling case with rather high quality scholarship over the past few years and I strongly recommend her blog. You shouldn't however neglect other forms of selection that have shaped humans recently and are relevant to the question. For example see Peter Frosts' arguments on genetic pacification and the fall of the Roman Empire.
Peter Frost thinks Christianity served as both a symptom and a cause, exasperating the trend to domestication causing decline when faced with less pacified peoples. A similar argument can be made about the f...
As Multiheaded added, "Personal is Political" stuff like gender relations, etc also may belong here.