This "look" at the issue is an overview and it is generally valid and true, but hopefully it is not an oversimplification.
Before the invention of the printing press, most families did not even own a book. Before the development of mass communication in the form of telegraph, radio, newspapers, and later telephone, most people were only exposed to the religious ideas that came from their own religion and its local leaders. Even then these media were largely confined within individual countries and cultures.
Before WWI most people even in the USA had never traveled in their entire lifetime beyond 50 miles from where they were born. WWI, mass transportation, and especially WWII inaugurated sweeping changes in the geographical, cultural and religious ranges of exposure that people experienced. In WWII, suddenly many American service personnel found themselves in Europe, Africa, the Orient, or on tropical isles, and with new companions from all over the country and all over the religious map. Some were even exposed to the great cities, for examples, London and Paris with their staggeringly diverse cultures, their extensive ranges of foods, music, arts, entertainment, and intellectual content, their multifarious values and ethics, including various modes of lifestyles, occupations and behaviors.
Now we have movies, television and the internet which have all but enturely breached sovereign borders and become international. The only significant inhibiting factor, outside of certain countries that control and limit access and the content, is the language difference, but these three media were largely developed in the USA where the language is almost exclusively English. Even before these media came into prominence, English had already become the de facto language of international science and commerce.
Along with all this has come to the world the introduction of formalized science and the scientific method, resulting in a veritable explosion of scientific investigation and knowledge in every possible discipline. This has literally blossomed into scientism, the world's now dominant religion, a religion which exists in conjunction with and resides somewhat uncomfortably right alongside the others, but to which all others must pay obeisance and usually surrender in cases of conflict.
Along these lines it should be noted that many (most?) of the oldest and most prestigious universities in the USA were founded as religious or theological colleges and have transitioned to being secular centers of learning. It isn't the English, Math, Engineering, History or Homemaking departments that pull these universities away, and this seperation is never promoted by the founding denomination, and yet more of these transitions are on their way.
What this means is that before these developments came about, the typical person in the world was only exposed to the local religion and philosophy. His religious options were essentially just three: 1) default to and settle into the religion of his local culture and family and become as best he could a devout believer and practitioner, or failing that, 2) become a careful and circumspect agnostic and hypocrite, or lastly 3) become an outcast or pariah to some degree.
Given that these religions only offered explanations of what went wrong, and usually why we are to blame for it not getting fixed alongside of coping mechanisms in the meantime; given that none of these religions ever delivered what we naturally need and want and proposed only the promise of "pie in the sky in the bye and bye", any real motivation came primarily from anxiety and fear.
Needless to say, the major limiting influences on the lifestyle, behavior, and pattern of life of those in the first two categories would have been peer pressure and societal norms instead of any inspirationally compelling vision or inner and solid, self-derived convictions. For the "believer" a major focus in life would be "fitting in" and the continued programming of indoctrination and reinforcement through sermons, service, symbols, rites, and ceremonies oriented to otherwise largely irrelevant beliefs, greater and greater amounts of the spiritual opiate. For the agnostic the focus of life would have been on not being squeezed out, mundane success and probably ill-concealed hedonism.
Any significant religious change and diversity for the eastern hemisphere in this older world came about primarily through invasions and alien political conquests and takeovers. For quite a time the two side-by-side dominant empires of Rome and Parthia were the major vectors of different religious influence because of their necessary need for police, military and political control of their far-flung territories. Of course, a certain level of international trade via caravans and ships was the other vector. Before Christianity, outside of military conquest there was almost no evangelistic outreach to other cultures and peoples.
Currently, those persons in the world with access to all the mass media are confronted with an overwhelming welter of religious and scientific paradigms, ideas and beliefs. Supposedly, there are over a billion websites now, millions of book titles in print, and the global community has now been spiritually fragmented into over 100,000 different identifiable religions. There is no sign that it is going to get less complex, no sign of any crystallization around any one religious philosophy.
And so yes, using this as a metaphor today we have drones and laser-guided missiles pitted against religiously programmed suicide bombers! Christendom and Islam are actually flirting around with the possibility of an out and out global religious war and there are those in both camps that would like to see this happen. As a consequence of diversity, how would that suit you?
Within Catholicism, the largest Christian denomination, long standing and major diversities have been accommodated and institutionalized. Even within a small and ostensibly monolithic denomination like Seventh Day Adventism−which makes some effort to keep everyone on the same page with a creed, central control, and its own parochial educational system−there are significant regional differences and the diversity of belief is ever so much greater than the organization can be willing to admit. In the Christian seminaries, there are certain subjects and questions that the theologians won't even talk to each other about, partly because of the futility regarding agreement and partly because of the fear of being branded a heretic or worse and the attendant career risk.
Given that there are two major scientific frameworks for much of what concerns religious thinking, uniformitarian and catastrophic, the gulf between these two is extremely wide and contentious. As is the gulf between two other frameworks, creationism and evolutionism. Creationism is generally thought to be aligned with catastrophism, and evolutionism aligned with uniformitarian, but what further underscores the diversity is that there are any number of hybrids and combinations. Just in terms of chronology and dating for the earth the gulf is between a few thousand years and "millions and billions".
Partly because of the revolt of Protestantism, the Reformation, partly because of the Renaissance, partly because of the French and other revolutions and the Enlightenment, partly because of the emergence of the United States and both its humanistic Declaration of Independence and largely Iroquois Nation-derived Constitution, and partly because of the travesty of the modern wars−primarily the two world wars and the horror of atomic weapons−Judaism and Christianity have been rocked, revolutionized and conditioned by humanism, but Islam has yet to undergo that transformation.
The Industrial Revolution was certainly a major factor that laid the foundation for such change. The significant increase in wealth and associated leisure time undergirded the blossoming of much more learning and more widespread education, travel, and exposure to diversity of experience and thought. Stir in the more recent Technological and Information revolutions and you have a further eruption of mind and soul affecting content, and all but destabilizing information overload.
* Philip Jenkins, "The Next Christianity", The Atlantic Monthly, 2002
Nietzsche and the existential philosophers have been a significant wake-up factor for western civilization, and the "God is dead" movement for Christianity. The dramatic development of the "science of the soul"−Psychology−initiated by the great psychoanalytical philosophers, Stekel, Velikovsky, Freud, Adler, Jung, Rank, et al, has had an emphatic influence. Advanced education in the enlightened world−because of several disciplines, not the least of which is psychology−has lessened the belief in a literal Devil and the influence and hold of the "God or the Devil done it" thinking. That has left "western", "humanistic" society more inclined to look at ourselves for being responsible and more and more leaving God out of the equation.
However, one cannot deal with religious diversity without remarking about the MONUMENTAL development of Christian growth primarily in the continents in the southern hemisphere excluding Australia. This increase has happened through both "conversions" and the exploding population growth. What is pertinent about this elephant in the living room is the less intellectually responsible, "conservative" nature or flavor of this Southern hemisphere Christianity. In general this is in stark contrast to the ever more "liberal" and humanistic brand of the Northern hemisphere, and going in the opposite direction.
One of the perspectives on this most significant diversity between the Northern hemisphere Christianity and that of the South is that in the North people live in relatively stable governments, are not poor by world standards, and have access to better nutrition and modern medical care as well as a greater variety of entertainment and diversion. These latter factors actually have a marked effect on population control.
Mysticism in religion opens the door to all kinds of intellectual chicanery. Many of the more humanistic, "liberal" Christians of the North have had quite enough of the above referenced "preaching" or focus on the arcane aspects of a literal Devil, exorcisms, witches, demon possession, primitive orthodoxy, rites, ceremonies, sacred iconography, bogus miracles, faith healings**, etc., and spiritual authorities that use political and base psychological maneuvering, pressure, power and control.
Many of the Southern hemisphere Christians live in situations where they cannot count on the corrupt civil authorities to give them the kind of basic physical, legal, and land ownership security that the Northern Christians take for granted.
The somewhat current population and percentages of Christianity for these two hemispheric arenas, excluding both Asia and Australia, are:
about 83.5% Christian
As can easily be seen with the above numbers, the Southern hemisphere Christians are in a majority, and because these two general versions are so incompatible, there IS a looming conflict of great moment, a confrontation that will make the Sunni versus Shiite struggle pale by comparison.
What are we to make of this unseemly spectacle of confusion, diversity and darkness in understanding the ultimate realities of who we are, our origin and our destiny, how much immediate, effective healing is available regardless of its source, and how should we then live? No comfort can legitimately be found by being in a majority because there IS NO majority! And the trend in Protestantism seems to be further denominational fragmentation if not stagnation in the North.
Since most of them are somewhat uncomfortable with the diversity or disunity and understand that their masthead, the J-person, made a pronounced call for unity, Christian leadership lives in a somewhat anxious state because of the lack of it. In Northern hemisphere Christianity there are periodic calls and surges of discussion for it. But what has been the result?
What should be abundantly clear about the above overview of religious diversity is that truth−partially at least, identifying the proper metaphysical principles, learning the salient information from the scientific findings, sorting out the theological issues, and philosophically dealing satisfactorily with the ultimate issues−has very little if any impact on these rather mundane sociological or "practical" developments in formal religion, be it either Northern or Southern.
One further point of fundamental context is that we remain still being pushed around in the back by Thanatos, the avoidance of death, and still being pulled around through our noses by Eros, the seeking of fulfillment. The human condition, characterized by the utter failure in both of these enterprises, reigns supreme with no end in sight.
A partial list of questions that can and should be asked:
1. Why do we need any "religion" beyond humanism?
2. Given that there IS singular truth, paramount questions hang there for us like gravid clouds in an oppressive, stormbound sky:
** This is not to say that all paranormal "miracles and faith healings" are bogus. The bicameral brain-mind of humans is a powerful thing and its capability and potential are dimly understood. No doubt that there HAVE throughout history been actual paranormal phenomena including "miraculous" or paranormal healings. The question is whether God is ever effectively involved, or to what degree, and whether God's involvement is encouraged and effectuated by devotion to and practice of this type of religion.