What We Think We Know About Religion in America

A new survey published by Grey Matter (HT: Joe Carter) shows that Americans know just exactly how many Americans are Roman Catholic (24%) but they underestimate the percentage by about 150%. They overestimate the percentage of Mormons, Jews, and Muslims by a considerable percentage.

The study says:

In reality, according to the 2008 U.S. Religious Landscape Survey from the Pew Forum on Religion and Public Life, Americans are right on target with the proportion of Catholics and the “all other” category, but way off target on the rest of the landscape.


The typical American badly underestimates how many Protestants there are in the country, and way overestimates the presence of religious minorities such as Mormon, Muslim, and atheist/agnostic.


In the United States, 51% of all adults affiliate with a Protestant belief system, denomination, or church, compared to the average estimate of just 20% in the Grey Matter Research study.  In fact, just 12% of all Americans believe Protestants make up at least half of the population in the U.S.

Why do Americans overestimate some groups and underestimate others? Is it a perception based on experience or media representation or both (or something else)?

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  1. I think the reason is akin to the same reason why a lot of Americans believe that the vast majority of their fellow citizens are probably primarily liberal in orientation. It just happens that most Americans are somewhat conservative in their politics, but the smaller liberal population is louder and more outspoken. The same would go for atheists.

  2. It’s interesting that every group except Protestants overestimated the size of their own group.

    “Americans know just exactly how many Americans are Roman Catholic (24%) but they underestimate the percentage by about 150%.”

    I’m having difficulty parsing this.

    • According to the study, Americans know/guessed the correct percentage of Roman Catholics but they had no idea what percentage of Americans are Protestant. They were off by 150%. That’s very interesting. Why are we so aware, apparently, of the statistical place of Roman Catholics in our country but so unaware of the percentage of Protestants? Well, when was the last time you saw a likable Protestant on TV? The dad from 7th Heaven was a bland Protestant minister. That’s it but there are lots of likable Roman Catholics on TV.They’re everywhere in the media but we’re invisible.

      There are other explanations, of course, that’s probably part of it.

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