I use the past tense here because although Christianity is still popular in terms of quantity -- professed numbers of adherents -- and collective in terms of ritual and practice, it has lost or is very rapidly losing its natural and social elements.
The popular and collective aspects of Christianity appear to be functioning, but beneath the surface these religious elements are in deep crisis for the simple reason that nearly everything popular and collective within Christianity is on the side that is openly opposed to God and Creation.
The positioning of these popular and collective elements has greatly diminished the natural and social aspects of Christianity, to the point that Christianity is now viewed as something so "unnatural" that it cannot be permitted to meaningfully influence any aspect of society, including the family.
To overcome this crisis of objective Christianity, the religion must become subjective and individualistic. This is the essence of what Dr. Charlton calls Romantic Christianity. I believe this subjective and individualistic form of Christianity is not only necessary but unavoidable.
Those who remain firmly committed to popular/collective forms of Christianity will inevitably be swept up by the world and ultimately cease being real Christians. Whether such Christians will ever acknowledge it or not is another matter entirely.
Thus, in the present, Christianity must become subjective and individualistic even if Christians continue to adhere to certain popular and collective religious conventions.
Does this entail that the Christianity will remain subjective and individualistic well into the future? I'm not sure, but if I had to answer, I would respond with both a yes and a no.
Yes, because at its core Christianity is a religion of freedom and love, which are both rooted in the personal -- that is, the subjective/individual.
No, because Christianity is also a religion of relationships -- a religion of spiritual beings freely connecting and interacting with each other at a personal level through love.
Whether these relationships ever become "popular" in the way objective/historical Christianity did is unknowable, but they will undoubtedly form some sense of a collective that is both natural and social.
However, this will entail a completely transformed understanding of what "natural" and "social" mean, and that understanding must first arise from the subjective and individual.
Therefore, the possibility of such developments depends entirely on what happens within the subjective and individualistic form of Christianity that is quietly emerging from the crisis of all that is popular and collective within the objective form of the religion.