Ask A Genius 1351: Intercessory Prayer Studies Show No Evidence of Divine Intervention
Author(s): Rick Rosner and Scott Douglas Jacobsen
Publication (Outlet/Website): Ask A Genius
Publication Date (yyyy/mm/dd): 2025/04/10
Scott Douglas Jacobsen: So, four studies often come up in the discussion on the inefficacy of intercessory prayer. In some cases, prayer not only fails to help, but even backfires. When people found out they were being prayed for, their stress levels went up — likely due to performance anxiety about recovery. That stress may have suppressed immune function, and across a large enough sample — like in clinical trials — their health outcomes were slightly worse on average compared to control groups.
So, here are the four key studies:
- STEP (Study of the Therapeutic Effects of Intercessory Prayer) — published in The American Heart Journal in 2006 by Herbert Benson and colleagues. It was a large, randomized, controlled trial.
- Francis Galton’s “Statistical Inquiry into the Efficacy of Prayer” (1872) — a historical essay in The Fortnightly Review, often cited as one of the first efforts to apply statistical reasoning to prayer.
- Harris et al. (1999) — published in the Archives of Internal Medicine, a randomized, double-blind trial assessing the effects of intercessory prayer on cardiac patients.
- The Cochrane Review on Intercessory Prayer — first published in 2007, updated in 2009, synthesizing data from ten randomized controlled trials.
All of these are staples in academic and peer-reviewed discussions about the efficacy — or more precisely, the inefficacy — of intercessory prayer. They are large-scale, controlled, and consistently yield neutral or negative results. Together, they underscore the failure to demonstrate any statistically significant benefit from intercessory prayer under experimental conditions.
And yes, citing Galton from 1872 adds historical weight.
Rick Rosner: 150 years ago!
Jacobsen: It’s a body of work that now includes modern data and rigorous methodology. The conclusion is fairly robust: when intercessory prayer is tested under controlled conditions, it performs no better than chance or placebo — and in some cases, may produce an “anti-placebo” effect due to heightened psychological stress.
Jacobsen: So what are your thoughts on that? What are your thoughts on prayer?
Rosner: Sadly, I don’t think we live in a magical universe. Unless you can propose a causal relationship — a mechanism by which something actually causes something else — things don’t just happen. If magic is the only possible explanation, then that thing probably doesn’t happen.
Even if we lived in a simulated universe — replicating one that itself wasn’t magical — a good simulation wouldn’t give away the game by leaving magical gaps. A universe with 10⁸⁵ particles, that’s at least 13.8 billion years old (and possibly much older, depending on model assumptions), doesn’t casually make room for magic. It runs on structure. On laws. On mechanics.
And the universe gives every indication that it reached its current form through a series of events — cause and effect, step by step. Of course, we do not know everything that has happened, but the things we have observed and studied show no evidence of magical intervention.
Unfortunately — because it would be comforting — the universe does not appear to contain a divine intercessor. It seems like we are on our own. If we want to live forever, there is no evidence for God.
And as you said earlier, there is no evidence for the efficacy of prayer. Would that it were. Would that we could pray and change our circumstances — that there were some benevolent being who loves us and would grant us continued existence after our bodies are gone. But the more we learn, the more it looks like that is not the case.
I mean, at various points — when I was younger — I sometimes convinced myself, briefly, that maybe under the rules of quantum physics there might be space for something magical to happen.
But I got over it.
Jacobsen: And keep in mind, some of those studies — the ones on prayer — involved thousands of participants.
Rosner: And yes, I mean, you could imagine a plausible causal chain. Like, if someone says they are praying for you, maybe that boosts your emotional resilience. Maybe you feel supported, which strengthens your will to recover. That’s a real, positive psychological effect.
But the key is, that’s not a magical effect. That’s your brain. That’s biochemistry, not divine intervention.
Jacobsen: And in some of the actual studies, even that did not show up. In fact, in the STEP trial, when patients knew they were being prayed for, their stress increased. Their health outcomes were worse, statistically, than other groups. So again, not only is prayer not magical — in some controlled cases, it has negative effects. So, given these empirical results — across multiple studies, in proper scientific conditions — what does this say about God?
Rosner: To some extent, God always exists behind a veil — a veil of the unknown. The biggest veil is death. We cannot see what happens after we die, and so that’s where many place the divine.
There’s another veil too: we can only see so far into the universe — into the deep past, into distant space. We cannot observe what happened at the exact moment of the Big Bang, if there even was one. And so people insert God there, too.
But our math keeps revealing more mechanisms — more ways that things can arise naturally. The models we build show how the universe could emerge through physical laws, without needing a divine creator.
When I was young — before you were born — there were tons of arguments like, “How could amino acids form? How could life emerge? How could complexity evolve?” And the answers were often: “It could not, therefore God.”
Those arguments are still around, but they’re weaker now. The gaps are smaller. The data is stronger. The explanations keep getting better — and they do not require magic.
And all those arguments — all those fucking things — keep getting knocked out as we discover plausible mechanisms that do not require God to explain how things came to be. The act of scientific investigation keeps expanding the boundaries of what we understand.
But no matter how far you push those boundaries, there’s always still a boundary — a horizon we have not crossed. And beyond that boundary? Sure, you can place God there if you want. But within the boundary — within the realm of what we can observe and explain — it just keeps getting more complete, more extensive, more sufficient.
I know it’s not a popularity contest, but I would assume that, over time, if you took all the people in the world who aren’t complete idiots, you’d see an increasing percentage of them becoming satisfied with scientific explanations for how the world works.
Jacobsen: So, when people pray — to the floor in Islam, to the wall in some forms of Judaism, to the sky in much of Christianity — what do you have to say to those devoted to prayer, in light of this evidence?
Rosner: I mean… I still pray. I’m a very science-oriented person, but I’ve been praying since I was a kid. When I was six, my parents went on a trip to New York for a week. When they came back, I was spinning in circles and chanting to God. That was the first time I got sent to a psychiatrist.
Rosner: Though, I guess under some religions, that would have made me special. But to my parents, it was more like, “Nope. That’s not good.”
I’ve got OCD. But I don’t pray just because of OCD. I pray because I hope — and fear — that there is something beyond. I don’t just go full analytic and try to “scientize” my way out of prayer.
Jacobsen: What does this mean with regard to the adherence to science and the suspension of it during prayer directly implied here?
Rosner: I believe in science. But I still pray. They’re not great prayers. But I still call on God. I wish there were a God. I don’t really believe there is one. But I still call on the possibility of God. I’m okay with that.
Jacobsen: You’re basically an aggressively agnostic theist.
Rosner: That’s fucking fine. And I’m okay with other people praying, too — as long as they’re not hypocritical dicks.
Rosner: Like, look — in the U.S., we’ve got Christian fundamentalists who are not Christian in any real sense of behavior. They’re just mean. They use religion to justify their cruelty. And I’m not okay with that. Fuck those people. You know — within reason. I’m okay with living this way. I’m not asking the universe to pierce the veil for me.
Jacobsen: I’m not asking if you’re okay with it. I’m asking if you think it’s true.
Rosner: Well… no. I don’t think it is.
Rosner: But we’re sad little fucking creatures. You’ve met our dogs, right?
Jacobsen: Are you saying… we’re the dogs?
Rosner: You met our dogs — one is smarter than the other. But still. Neither of them… one of them’s — I mean, one of them’s kind of clever in some ways. But they’re both… it’s sad. They’re sad creatures who live in a world they don’t understand and who die way too soon. And we’re not much better.
We are sad creatures too — at the mercy of biology, in a world we do not control, and where there’s still a ton of shit we do not understand. We’re pitiful beings, the product of evolution — an evolution that makes us want things deeply and then leaves us to die unfulfilled. We do not want to die. We want so much, and yet we have limited resources because we’re the product of limited, unguided creation.
And I think it’s totally valid — for us, these pathetic little beings — to turn our eyes to the heavens and say, “Please.” It fucking is.
Jacobsen: I’ve got another topic — something more positive.
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