To progress toward a better future, humanity desperately needs a better understanding of religion. Maybe microbes can help.

Religion is one of the most powerful forces in human society. Before the rise of America’s Christian Right and before Islamists turned planes into bombs and started beheading people on social media, many Americans thought of religion as a relatively benign institution or, at worst, one that was toothless and doddering. Sure, religion may once have had the power to burn libraries and infidels or rouse armies of crusaders, but that all seemed like distant history. In modern popular vernacular, that’s not very Christian of you simply meant not very nice, and Islam was said to mean peace rather than its other root: submission.

But as a psychologist and former fundamentalist, I have always had a healthy regard for the power of religious belief.

During my years in Evangelical Christianity, I heard the story of Nicky Cruz, a New York gang member whose life had been transformed by Jesus; the story of Chicago’s Union Gospel Mission that turned alcoholic bums into sober Christians; the story of missionary Elizabeth Elliot who dedicated her life to saving the souls of Amazonian headhunters after they killed her husband.

After I left Christianity, I heard stories of lives transformed in bad ways by religious belief—adults plagued by panic attacks from childhood threats of hell; families torn apart when one member restructured his or her life around religious scripts or, alternately, deconverted and was disowned; and devout parents who followed the Bible’s parenting advice, beat your son with a rod, to the point that they killed their children. I read letters from missionary believers who fantasized torture and death for anyone who blocked them from seeking converts on, say, public school grounds or military bases. I will pray The Word that our righteous Lord and Savior will smite you . . . First on the list: Pray the Lord to have Mr. Weinstein watch Mrs. Weinstein burn alive in a car accident.

Religion, like almost no other human enterprise, arouses a surprising percent of people to such heights of passion that they abandon all else and devote themselves to the propagation of religion itself—even when that means giving up their own life or taking the life of another. Even more moderate belief can drive people to do things that are shockingly altruistic, like taking in a homeless stranger, or shockingly cruel, like throwing their queer child out onto the streets. (These actions can also be shockingly at odds with the rest of their character.)

Some Christians say that we humans are, all of us, “utterly depraved” and that without religion—or rather Christianity specifically—the world would descend into End Times anarchy. Outsiders sometimes argue the opposite, that religious belief prompts fundamentally decent people to do horrid things they wouldn’t do otherwise. U.S. physicist Steven Weinberg put it this way: “With or without religion, you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion.”

“Is it a mental illness?” Because I am a psychologist, people sometimes ask me, quite seriously, whether religion—or at least religious fundamentalism—is a psychopathology. After all, most religions seem somewhat crazy from the outside. If someone were alone in believing that his child was going to be tortured forever unless they prayed a certain prayer—or if someone were alone in believing that a supernatural being cares whether you wash plates that have touched milk and those that have touched meat in the same dishwasher—or if someone were alone in believing that God wanted all women to walk around in black sacks with their faces covered—we might suspect that person was schizophrenic. But schizophrenia is caused by a breakdown of neurological systems within the individual, and religion is not.

Religious beliefs, however incredible they may be to outsiders, are held by millions of people who find their own bizarre convictions intuitively resonant and perfectly reasonable–and who are otherwise quite sane. Also, peculiarities aside, religions seem to bring out the best in some people, perhaps by enhancing altruism or providing community support for acts of generosity and compassion, or by disinhibiting wonder and joy. So, for years, I said, no, not a psychopathology.

But some similarities nagged at me. Take paranoid schizophrenia for example. Whatever the precise biological mechanisms may be, the person has a set of peculiar and powerful experiences which the mind seeks to explain. Over time, a whole plotline gets fabricated, with actors and motives and perceived relations between events that become self-confirming and utterly impervious to rational disconfirmation. Any attempt to challenge the story provides further proof that it is true.

Schizophrenic delusions tend to have some special features that are a consequence of how schizophrenia itself works (the person’s beliefs need to account for experiences like visual hallucinations, thought insertion, or hearing voices). But otherwise, the end product is not unlike many widely-held conspiracy theories and some forms of religious belief. The primary difference between a schizophrenic’s delusional system and a conspiracy theory or system of fundamentalist theology is that in schizophrenia the plot structure is triggered by a biological malfunction, is idiosyncratic (meaning that despite common themes it differs from person to person), and lacks social validation.

So, the causes are different, but the products are oddly similar; and over the years, the more I thought about it, the more I came to wonder if religious belief might be best construed not as psychopathology but as something related that I called a socio-pathology. By this I meant a delusional system that has its root not in a biological malfunction but rather in a malfunction of social information flow.

I now think that hunch was only partly right. To explain, I need to delve into the nature of the human mind, the nature of ideas, and the nature of religion—with a little help from bacteria.

Part I in a 4-part series. This series was first published as a single article in The Humanist – A magazine of critical inquiry and social concern. May/June 2017 issue, p. 16-21.

Valerie Tarico is a psychologist and writer in Seattle, Washington. She is the author of Trusting Doubt: A Former Evangelical Looks at Old Beliefs in a New Light and Deas and Other Imaginings, and the founder of  Her articles about religion, reproductive health, and the role of women in society have been featured at sites including AlterNet, Salon, the Huffington Post, Grist, and Jezebel.  Subscribe at