In the comments below I engaged in a little bit of glib dismissal in regards to the contention that a secular society is not sustainable. The issue though need some elaboration. I agree with John Derbyshire when he says:
Mark: “Can humanity survive over the long term without religion?” To my way of thinking, that’s like asking “Can humanity survive over the long term without music?” Religion, like musical appreciation, is just a feature of the general human personality, arising from the structure of the human nervous system. The religious impulse is more developed in some of us than in others, and a few of us are completely tone deaf (though that’s no reason to exclude us from non-musical discussions); but most human beings enjoy a good tune at some level. It’s human nature.
Religion, broadly construed as acceptance of supernatural agents, gods, and the powers associated with such beings, is universal, and has a high degree of penetration in most societies. In some societies, such the Middle East or Africa, acceptance of supernatural agents is universal in a literal sense (the World Values Survey shows that of 2,000 respondents in Pakistan not a one admitted to being an atheist!). But even in avowedly secular societies, such as in Europe or East Asia, the majority do not deny the reality of the supernatural.
On the other hand, intellectual historians are prone to noting that East Asian societies give less pride of place to religion than those of South or West Asia, or Europe. What’s going on here? Religion, narrowly construed as a prescribed set of behaviors & beliefs, an elaborated and robust collection of institutions, as well as a deep philosophical tradition, integrated together into an organized whole, is much less a pervasive feature of East Asian society (in early Tang China, Fujiwara Japan and Silla Korea a form of Buddhism came close to taking a central role within the society analogous to that of Christian and Islam, but it did not “take”). Terms like “folk Christianity” or “folk Islam,” as well as the philosophical schools within these religious traditions, are witness to the reality that religious expression is very diverse. But in what was Christendom, what is the Dar-al-Islam, these diverse traditions have been tied together by a catchall framework. The elites of the pre-modern West, and the contemporary Islamic world, may have espoused, or do espouse, personal religious beliefs which are alien to the masses in terms of their sophistication, but notionally the elites and the masses are of the same religious tradition or stream. In contrast the Confucian bureaucrats who administered the polities of pre-modern China and Korea, as well as Tokugawa Japan, self-consciously understood the distinction between their own attenuated beliefs in the supernatural, which might have gone no further than ceremonial deism, and the baroque folk religions which were dominant among the masses. In this way they likely resembled the cultural framework dominant during the Greco-Roman period, when a multiplicity of folk traditions divided the loyalties of the populace while the elites dabbled in abstruse philosophy and obscure mystery cults.
So far this has been purely descriptive. That is, I’m describing what seems to be the reality across human history. A substrate of normal supernatural belief, reshaped and organized in some locales around the aegis of a monopolistic cult. What is the future? The secularization of Europe obviously does exhibit some level of rejection of the supernatural; after all, 33% of the French adhere to the atheistic position. But there are data that show that the decline of Christianity in Europe, the loss of its public monopoly, has been met not by the rise of a godless monopoly, but the resurgence of supernatural pluralism. In other words, the future of Europe may resemble the situation in many East Asian nations, where a large fraction of the population are rejectors of the supernatural, but an even larger proportion operate as freelance subscribers to a hodgepodge of supernatural beliefs and practices, and another fraction adhere to one of the world religions.