Or, to put the question more precisely: how internally diverse are each of the world’s religions?

Most people understand that the religious landscape is a very diverse place. A plurality of different religions, major and minor, exist in the world, each believing different things. Judaism is different from Hinduism; Christianity is different from Buddhism. Islam is different from Taoism; Wicca is different from Scientology.

But a lot of people who fully understand this “external” religious diversity — there are lots of religions, and each one differs from all of the others — may not fully grasp or fully appreciate just how diverse each individual religion itself actually is, within its own boundaries or parameters.

In other words, not only does an external diversity of religions exist, but considerable internal diversity also exists within each major religion.

Many who are new to the study of the world’s religions sometimes tend to assume that everybody within any given religion believes and practices in pretty much the same way. They just assume that all Hindus believe the same things, or that all Buddhists practice the same ways, that all Muslims are essentially united on matters of belief and practice, and so forth.

Nothing could be further from the truth.

To be sure, there are broad areas of general agreement, particularly where some of the basic core concepts and behaviors are concerned. However, this general uniformity can easily mask other areas of deep disagreement and division, which also exists within each of the world’s major faiths.

I assume that a majority (but by no means all) of my readers are probably Christians of one sort or another, in part because Christianity is the single largest religion in the world, and in part because North America as a whole is itself about 80% Christian. A moment’s reflection on the part of my Christian readers will confirm the fact that their own religion — Christianity — is, in fact, characterized by immense internal diversity.

That very phrase — “Christians of one sort or another” — implies that there are multiple such “sorts” of Christians. As, indeed, there are.

There are Roman Catholic Christians, and Eastern Orthodox Christians, and Protestant Christians. Within Orthodoxy alone, there are Russian Orthodox Christians, and Greek Orthodox Christians, and Romanian Orthodox Christians, and quite a few others. Within Protestantism alone, there are Baptist Christians, and Methodist Christians, and Lutheran Christians, and Presbyterian Christians, and Episcopalian Christians; there are also nondenominational Christians and Pentecostal Christians, evangelical and fundamentalist Christians, Amish and Mennonite Christians, Quaker and Mormon Christians, and many more besides. “Christianity” is not one thing, but many.

Now, that’s diversity. And the thing is, that sort of internal diversity is not limited to Christianity alone. It exists, to varying degrees, within each of the other major world faiths, as well.

Judaism is internally diverse. Within Judaism today, one can find Orthodox Jews, and Conservative Jews, and Reform Jews. There are Reconstructionist Jews, and Haredi (including Hasidic) Jews. There are even Jewish mystics, known as kabbalists. Despite their differences, of course, they are still all Jews. Judaism today is not one thing, but many; even so, it’s still all “Judaism.” Internal diversity exists within a broader and overarching unity.

Islam is internally diverse. There are Sunni Muslims, and there are also Shi’ite Muslims. Within Sunni Islam, there are subdivisions and sects — for instance, the Wahhabi movement, dominant within Saudi Arabia. Within Shi’a Islam, there are also various sects and subgroups, among them the so-called Twelvers, the Seveners, the Fivers, and others. There are even Muslim mystics, known as Sufis. But again, they are all Muslims. Islam, like Judaism and Christianity, is not one thing, but many.

Buddhism is internally diverse. Within Buddhism today, one can find Theravada Buddhists in southeast Asia, Mahayana Buddhists in China and Japan, and Vajrayana Buddhists in Tibet. Within Buddhism’s Mahayana branch, one can find a bewildering diversity of Buddhist belief and practice; there are Pure Land Buddhists, and Zen Buddhists, and Nichiren Buddhists, among others. Many of these various Mahayana sects themselves subdivide even further into subsects — into Rinzai Zen and Soto Zen, for instance, or the four different Japanese Pure Land sects. Once again, internal diversity seems to be the rule within Buddhism.

Hinduism, too, is internally diverse. There are Vaishnavite Hindus who worship Vishnu, and Shaivaite Hindus who worship Shiva. There are Hindus who worship God as a Goddess, and there are even a multitude of such feminine forms of the Goddess from which to choose– Kali or Durga, Lakshmi or Saraswati, Parvati or Uma, to name a few. There are devotees who offer loving devotion to a personal deity (again with a multitude of options — Krishna, Rama, Ganesha, Hanuman, etc.), and there are yogis meditating in mystical pursuit of union with Brahman, the impersonal World Soul or Supreme Reality. So again, within Hinduism alone, vast diversity reigns.

Such internal diversity seems to be the norm within all of the major world religions. No religion of any size, it would seem, is uniformly monolithic or homogeneous, identical throughout, with all of its members believing in exactly the same things and behaving in exactly the same ways. To avoid oversimplification and misunderstanding when setting out to explore the world’s great faiths, this pervasive characteristic reality is something always to keep in mind.

Never assume, when talking to individual Hindus, Buddhists, Jews, Christians, or Muslims, that you already know pretty much what such individuals actually believe. There is simply far too much internal diversity within each individual religion to make such an assumption likely to be correct.

Instead of making such assumptions, simply ask them what they believe, instead. And listen openly and carefully to their answers.