Verified by 
The merest acquaintance with the humans on planet Earth and their religions immediately raises two questions: (1) Why are there so many religions? and (2) Why are religious people so immune to data that concern their religion? In this post, we will address the first question.
Well, how many religions are there? First, we should restrict this question to religions that exist today, and exclude all the religions that came and went (and are now lost) during first 190,000 years of Homo sapiens. And, of course, we acknowledge that estimates vary. But none of the estimates are small. So now: There are dozens of major religions (varying between a couple dozen and four or five dozen). By “major” I mean religions with at least half a million adherents or so. These religions differ significantly from each other in doctrine, in the deities or sacred beings they worship or acknowledge, and in how anything supernatural is perceived. (Many of us learned in school that there were five major religions: Christianity, Islam, Buddhism, Hinduism, and Judaism. This seriously understates anything like the correct number.)
The dozens number is not the interesting number, however. The interesting number is the number of sub-religions under each major religion. Often, these sub-religions, or sects, or groups, differ almost as much from each other as the major religions differ among themselves. So, for example, some experts estimate that there are over 30,000 versions of Christianity. Arguably all these versions worship some version of Jesus Christ, but beyond that, they differ significantly. For example, some see Jesus Christ as a sort of warrior against sin; some see the Christ as a god of love, unconcerned about sin; still others regard Jesus as a male human being who managed to live the perfect life and should therefore be emulated. There is also considerable mixing and matching. All of what I’m calling the major religions break up into at least several and often thousands of different sects or groups.
Let’s sum this up by saying that there are tens of thousands of religions on planet Earth today. This number is conservative.
OK, now why are there so many religions? Here’s where things get interesting.
Perhaps the most popular religious answer to this question is that we are each seeking our own path to God, and our own paths vary because we vary. (Though I capitalize the word “God”, it is important for this explanation that I do not mean any specific deity of any specific religion. And I don’t.) But this explanation is flatly denied by many of the largest religions in the world today (religions with the most adherents). Most Muslims, Buddhists, and Christians do not subscribe to this explanation. They think their religion is the correct one and the others are not. But the crucial fact to note here is that this explanation turns the existence of the tens of thousands of religions into merely a side-effect of the fact that there are billions of religious humans. On this explanation, therefore, the existence of thousands and thousands of religions is rendered not interesting.
A much better explanation can be derived by taking seriously the existence of the thousands and thousands of religions. It is not a side-effect; it is the key. Taking this fact seriously means looking for an explanation of religion that has as a consequence the fact that there should be thousands and thousands of religions. We need to look only as far as evolutionary theory. There are thousands and thousands of religions because being religious is an evolutionary adaptation. Evolution produces lots of variation within the parameters of a given type of adaptation (there is a huge variety of feathers, for example). If religions were or are doing something positive for human well-being and psychology (even if religions cause many serious problems) then religiosity will be preserved. But if the religious details don’t matter, then evolutionary theory predicts that there will be thousands of religions. Which is in fact what we see.
Consider an apt analogy—language. All people speak a language—no matter how isolated. Language evolved from animal communication. All living things communicate. But only humans use language. At least that is the current view. Note that there are and have been thousands of languages on planet Earth. Why the vast number of languages? The answer is that the details of the language spoken are not relevant to communication. All that matters are that the sounds have meanings and follow a grammar of some sort. These are very loose constraints. Since the constraints on languages are so loose, languages vary wildly in their sounds, structures, and compositional meanings. This explains the large variation in languages. The same is true of religion. Religions are like languages. Religions are an evolutionary adaptation primarily for keeping groups and tribes together. This job can be accomplished in a huge variety of ways. And that’s why there are so many religions.
