Is nobody really excited about the stuff science is actually discovering as we speak? I mean seriously...Science is not a belief system. It evolves and changes as new facts emerge. The main religions, by definition, have all the answers already, often in spite of evidence to the contrary. (I hate comparing the two and only mention it because somebody mentioned science as a belief system...).
Those of us educated as scientists call science a belief system. We believe that we have developed methods that are rigorous in their application. Over history, we have found flaws in what we thought were the scientific principles and have adapted. No scientist thinks we have it "right". No scientist thinks we ever prove anything, either, we simply collect more evidence, use it to review theories on this and that and adapt the theories as best suits available evidence.
And, while science seeks to provide mathematical models that help predict immediate future events, it is done with the clear understanding that we do not know reality. As is true for all humans, there is a reality, but nobody sees it truly...to a human, reality enters our awareness through our senses, which themselves are inaccurate, having been adjusted, adapted and trained through our lifetime of exposure to preconceived notions. Similarly, the tools of science were developed in response to what science believed about life, the universe and everything...and we are keenly aware that they are biased in ways we cannot fathom. Thus, science does not even pretend to be able to describe the fundamental nature of a thing.
For instance, while we have mathematical constructs about gravity and what it affects - we don't fundamentally know its nature - what causes it? And, without that, we don't know if there are ways to modify it, temporarily suspend it in local areas, etc. As much as many people revere science, it is still at a fundamentally base level, having but scratched the surface of anything it's touched so far.
What do you consider a "major religion?" Hinduism and Buddhism, which have more in common than different, represent the overtly stated belief system of approximately 25% of the world's population. And they are infused deeply and inform the cultural norms of the two most populated countries in the world.
An interesting note on China and religion. In 1949, the Communist party supposedly banned religion in China. But a person's beliefs don't change by legislation. So, it actually took until about 1980 before the government believed they had control over religion - but had not yet quashed it. Realizing that people will believe, and there's an inherent human need to answer certain questions (what is my role in the cosmos? what must I do to successfully navigate life's challenges such as adulthood and old age?), the government released, gradually, its hold. As of today, the Chinese government formally recognizes (e.g. gives favored tax status and legal protection) to five religions: Buddhism, Taoism, Islam, Protestantism and two flavors of Catholicism.
Technically, "Religion" differs from "spirituality" in that a religion has formal rules, usually a governing body, and tends toward unwavering support of existing beliefs, with little permission for adjustments with time. Spirituality is more about the search for the essence of who you, as a person are, especially in regards to how you are connected to "all of it" - other people, the animal and plant kingdoms, the planet, the cosmos.
Anybody raised in a culture with a dominant religion is narrow-minded in a sense. Those of us raised in the USA have certain beliefs about religion. We often believe that all religions believe in a God. We often believe that all religions seek to expand, and that they have a heaven and a hell, and that there's a set of rules that adherents are supposed to follow or else be punished somehow. These beliefs, however, were originated in Christianity, and do not exist in older beliefs.
Judaism, as the precursor to Christianity, introduced a few of Christianity's principles...while Judaism believes in the existence of many Gods, there is but one who created all this, and deserves our worship. I am told by the fluent biblical Hebrew speakers that I know, that "deserves our worship", in the vernacular of the day, does not literally mean to pray to this god, but rather to acknowledge their importance - and our kinship. All older belief systems perceived that there is some larger consciousness than the individual human, and this larger consciousness (which may or may not have a will) is a product of all life...therefore, we "owe" this thing, because we formed it. It is as our offspring...but we are not superior to it, since no single one of us created it...it came about without us intentionally doing it. This particular method of observing the transcendent (transcendent means "too big for words") isn't how Jews observe today, but there's plenty of anecdotal and other evidence from back then that it was probably the case.
It would not be until Christianity was formalized (and became the first written religion) that rules were written, strictly believed that they must be followed, etc. Before that, the belief systems were meant as guides - behave this way and your life will go more smoothly, rather than behave this way or get punished.
Anyway, the belief systems that do not include a god as a being separate from humanity actually represent a greater proportion of the world's population than those that do believe in a non-human god. Anybody raised in a society with a dominant belief system is, without question, partially formed by it. In the US for example, most atheists believe that religions all believe in a God...and that's just not true. (Science can prove something false simply by finding one example in which it is not true - proving something true is nearly impossible). And, in the US, most of the population believes that religion and science are opponents - but once you get away from Christianity-based religions (which includes Islam, Mormonism and many other younger beliefs), the belief systems inherently believe that science will inform them and they'll make changes in the belief system to accommodate the new information. If you go back 5,000 years, religion WAS science - the early priests studied the movement of the stars and planets and took the knowledge to use as a method for organizing human culture. Constellations became cities, stars with planets were used to model placing governments in the center of populations, etc.
So - science IS a belief system. And, like Hinduism, Taoism, and many others, it does its best to be evidence-based. And it knows it doesn't have it right yet, just like most religions.
BTW, this is kind of timely for me...a year ago I got introduced to the works of Joseph Campbell and have been devouring his hours and hours of lectures on mythology and comparative religion - his angle was unlike any other. Instead of looking at variations in religions belief to identify what is different from culture to culture, he tried to find the basic seeds that were common to all - beliefs that existed in cultures that had no way of knowing each other. These common beliefs, he felt, were a clue to the innermost truths of the human soul and existence.