There are few things that both unite and divide people as effectively as organized religion. Up until modern times, nearly every civilization, society and empire has been affiliated with a particular belief system. Religion is one of the defining features of a culture, and one that can affect nearly every aspect of daily life, including clothing, diet, occupation, recreation and education. Although a wave of secularism in modern times has caused organized religion to wane in many regions of the world, it still remains a powerful geopolitical force and important aspect of billions of people’s lives.
The sharing of a particular set of beliefs and values has effectively united groups of people throughout history, and because groups of people are usually associated with particular geographic areas, religion too is linked to specific regions. Much like language, religion has been one of the defining means by which groups of people have differentiated themselves from other groups of people. In this way, religion helps to form a cultural border around a group of people that separates them from other cultural groups, and helps maintain solidarity within. Integrated with other aspects of culture, religion has formed the basis of countless civilizations and empires, and has been one of the dominant forces in the development of the modern nation-state.
Religion, like other aspects of culture, exhibits a very distinct geographic pattern. The spatial distribution of major religious groups results from the migration of people and the spread of religious ideas from one place to another. Much like language, organized religions, and the religious ideas and values that give rise to them, typically originate at some central location and diffuse outward, often evolving into sub-religious groups (much like regional dialects) as they expand. Islam, for example, originated on the Arabian peninsula in modern day Saudi Arabia around the year 632 C.E., and spread outward as far west as Spain, as far east as Turkmenistan, and as far south as Sudan, in just three centuries. Through military conquest and the spread of the new Islamic religion, the Arab Empire became one of the largest in history by the end of the 8th century.
While all religions have a region of origin, many also center around a particular holy city and/ or group of sacred spaces. Jerusalem, for example is a holy city of the three major Abrahamic religions: Judiasm, Christianity and Islam. In Islam, however, Mecca is the most holy city on Earth; it is the birthplace of the Prophet Muhammad, the founder of Islam. In Christianity, Rome is home to the Papacy and has served as the center of the Roman Catholic Church for over 1,600 years. Christianity is an example of a religion that arose in one place (modern day Israel), found a new cultural center (Rome), and is now almost entirely absent from its place of origin.
For many religions, rivers and other natural features of the landscape serve as sacred spaces and hold special meaning for followers. For example, the Jordan River along the eastern border of Israel is sacred to Christians, while Ganges River is sacred to Hindus and Mount Fuji is sacred to Shintoists in Japan. There are also countless sacred structures, many concentrated in holy cities, built to honor deities and other religious figures.
Although there are dozens of organized religious throughout the world, only three are considered major universalizing religions because they actively seek to convert non-believers and members of other religious groups: Christianity, Islam and Buddhism. The desire to universalize their teachings has had a profound impact on the size and geographic distribution of these religions. It is no accident that the three religions have over 4 billion followers, more than half the world’s population.
Organized religions that are not universalizing (or proselytizing) tend to remain relatively small or at least bound to a particular geographic region. They are also usually associated with a single cultural group. Hinduism, with about 1 billion followers, is the largest non-universalizing religion, but is limited to India and parts of southeast Asia. As suggested by its size and reach, Hinduism was in fact a universalizing religion thousands of years ago when it spread eastward from the upper Indus Valley. Shintoism, Judiasm and Sikhism are examples of smaller non-universalizing religions also associated with distinct cultural communities.
In addition to religious values, the spread of organized religions was also the result of technological and economic forces. Today, the populations of Middle and South America are overwhelmingly Roman Catholic. Roman Catholicism is not only a universalizing religion, it happened to be the dominant religion of Spain and Portugal, the two dominant seafaring nations in the 15th and 16th centuries, and the first two countries to reach the New World. Once there, the Spanish and Portuguese conquerors and missionaries set about converting the local populations to Roman Catholicism. Further to the north, however, English, Danish and Dutch immigrants settled the East Coast and Midwest regions of the present-day United States, bringing with them their Protestant Christian religion.
Although much later waves of immigrants from Ireland, Italy and France would increase the proportion of Roman Catholic followers in North America, Protestanism would remain the largest religion in the United States and much of Canada. The Protestant sect of Christianity is also the dominant religion in other regions settled by northern Europeans, including South Africa and Australia.
Today, Christianity – both in terms of number of followers (about 2 billion) and land area – is the largest major organized religion. It’s followers can be found throughout the world, but most notably in North and South America, Western and Southern Europe, Russia, Australia/ New Zealand, and parts of Sub-Saharan Africa. Islam is the second largest religion, with about 1.5 billion followers. Followers of Islam (Muslims) can be found throughout northern and eastern Africa, the Middle East, central Asia, and much of Indonesia.
Both Buddhism and Hinduism have between 500 and 1.5 billion followers and their followers collectively cover much of southern and eastern Asia. Many regions of the world have been moving away from organized religion and towards secularism (freedom from religious rule and teachings). These areas include most notably China, Europe and Russia, and parts of North America. The percentage of the non-religious has reached 90 percent in China and parts of Scandinavia.