A big failing in my definition was that it omitted a second attribute of religions: they are also social movements of people who identify themselves as sharing deeply held beliefs. Someone who believes in a god and in a long list of other doctrines that he invented, and who devotes part of every Sabbath to sitting in a room by himself, praying to that god, and reading a book that he has written himself but shown to no one else, doesn’t qualify as practising a religion. The closest actual equivalent to such a person is hermits who live in isolation and devote themselves to prayer. But those hermits arose from a community of believers who provided the hermits’ beliefs, and who may continue to support and visit the hermits. I’m not aware of hermits who devised their own religion from scratch, went off into the desert to live alone, and refused food offerings and discouraged visitors. If someone should show me such a hermit, I would define him as a non-religious hermit or else as a misanthrope, while others might consider him to be a typical religious hermit except for failing the test of sociality.
A third attribute of many religions is that their adherents make costly or painful sacrifices that convincingly display to others the adherents’ commitment to the group. The sacrifice may be of time: e.g., interrupting other activities five times per day to face towards Mecca and pray, or spending part of every Sunday in church, or spending years memorizing a complex ritual, prayers, and songs (possibly requiring learning another language), or devoting two years to missionary activities as a young adult (expected of Mormons), or joining a crusade or a pilgrimage or visiting Mecca at one’s own expense. The sacrifice may be of money or property donated to the church. One may offer a valuable domestic animaclass="underline" one sacrifices to God one’s own lamb, not some captured wild animal that cost nothing. Or the sacrifice may be of one’s bodily comfort or integrity, by fasting, chopping off a finger joint, circumcising or subincising (splitting lengthwise) the penis, or spilling one’s blood by cutting one’s nose or tongue or penis or inside the throat or other body part. All of those costly public or painful displays serve to convince other believers that one is serious in one’s commitment to their religion and will even sacrifice one’s life if necessary. Otherwise, if I merely shouted “I’m a Christian!,” I might be lying for personal advantage (as some prisoners do in the hopes of gaining parole), or to save my life. While the second and third attributes (i.e., a social movement and costly sacrifices) seem to me necessary conditions for a movement to count as a religion, they’re not sufficient conditions by themselves. There are also non-religious social movements sharing deeply held beliefs and demanding costly sacrifices of their adherents, such as patriotism.
The next-to-last attribute of religions is that belief in gods and other postulated supernatural agents has practical consequences for how people should behave. Those rules of behavior may variously take the form of laws, moral codes, taboos, or obligations, depending on the type of society. While virtually all religions have such rules of behavior, it is not the case that rules of behavior stem only from religion: modern secular state governments, countless non-religious groups, and atheistic or agnostic citizens also have their own rules.
Finally, many religions teach that supernatural agents not only reward virtuous rule-obeying people and punish evil-doers and rule-breakers, but also can be induced by prayers, donations, and sacrifices to intervene on behalf of mortal petitioners.
Thus, religion involves a constellation of five sets of attributes, which vary in strength among the world’s religions (including traditional religions). We may use this constellation to understand the differences between religion and several related phenomena that share some but not all of the attributes of religion. Patriotism and ethnic pride resemble religion in being social movements distinguishing their adherents from outsiders, demanding sacrifice (even of one’s life) as a display of one’s commitment, and celebrated in rituals and ceremonies such as (for Americans) Independence Day, Thanksgiving Day, and Memorial Day. Unlike religion, patriotism and ethnic pride do not teach belief in supernatural agents. Sports fans, like religious believers, form social groups of adherents (e.g., Boston Red Sox fans) distinct from adherents of other social groups (e.g., New York Yankee fans) but don’t espouse supernatural agents, don’t demand great sacrifices as proof of affiliation, and don’t regulate a broad range of moral behavior. Marxism, socialism, and other political movements do attract committed groups of adherents (like religions), motivate adherents to die for their ideals, and may have broad moral codes, but don’t rely on the supernatural. Magic, sorcery, superstition, and water-witching (the belief that underground water can be located by a divining rod) do involve belief in supernatural agents with consequences for everyday behavior. However, magic, superstition, and related phenomena do not serve as defining attributes of committed social groups akin to believers: there are not groups of believers in the dangers of black cats who meet every Sunday to re-affirm their separateness from non-believers in the dangers of black cats. Perhaps the grayest borderline area involves movements such as Buddhism, Confucianism, and Shintoism, about which there are varying degrees of uncertainty whether they constitute religions or else philosophies of life.
Functions and electric eels
Religion is nearly universal in humans, but nothing even remotely resembling it has been described in animals. Nevertheless, we can inquire about—indeed, we have to wonder about—the origins of religion, just as we wonder about the origins of other uniquely human traits such as art and spoken language. Six million years ago, our ancestors were apes that surely lacked religion; by the time that the first written documents appeared around 5,000 years ago, there was already religion. What happened in the intervening 5,995,000 years? What were religion’s antecedents in animals and in human ancestors, and when and why did it arise?
A method termed the functional approach has been the commonest framework adopted by scholars of religion since they began studying it scientifically almost 150 years ago. They ask: what functions does religion fulfill? They note that religion often imposes heavy costs on individuals and societies, such as impelling many people to live celibate lives and to forgo having children, to go to the effort and expense of building huge pyramids, to kill one’s valuable domestic animals and occasionally even one’s own child and oneself, and to spend much time repeating the same words over and over again. Religion must have functions and bring benefits to offset those heavy costs; otherwise, it wouldn’t have come into being and couldn’t be maintained. What human problems did the invention of religion solve? A brief summary of the functional approach might be to assert something like this: religion was invented in order to carry out certain functions and solve certain problems, such as maintaining social order, comforting anxious people, and teaching political obedience.