WASHINGTON (RNS) — Most Americans know what an atheist is and why Christians celebrate Easter, according to a recent survey by the Pew Research Center.

But only 20 percent identified Protestantism—and not Catholicism—as teaching that “salvation comes from faith alone” rather than through both faith and good works. Only 34 percent knew that according to Catholic teaching, the bread and wine used for Communion are not symbolic but actually become the body and blood of Christ. Perhaps more surprisingly, among Catholics themselves, only 50 percent correctly answered the question about transubstantiation, while 45 percent of Catholics said that the bread and wine in communion are only symbolic.

Some elements of Christianity were widely known: 81 percent of all Americans said that Easter celebrates the resurrection of Christ, and 79 percent identified Moses as the biblical figure most associated with leading the Exodus from Egypt. Eastern religions were not as familiar: Only 18 percent could identify the “truth of suffering” as one of Buddhism’s “noble truths,” and only 15 percent could state that the Vedas are prominent Hindu scriptures.

Only 50 percent correctly answered the question about transubstantiation, while 45 percent of Catholics said that the bread and wine in communion are only symbolic.

The report on American religious literacy, released on July 23 by the Pew Research Center, reveals some of what Americans do or do not know about their own faiths and others.

“I was struck, for example, that just one in five American adults knows that Protestantism, not Catholicism, traditionally teaches that salvation comes through faith alone,” said Greg Smith, associate director of research at Pew and one of the primary researchers for the report. “I was struck that only about a quarter of Americans know that Rosh Hashanah is the Jewish New Year.”

The report was based on a survey of 10,971 respondents who answered online multiple-choice questions about religion.

Less than 1 percent of respondents got a perfect score on the 32 survey questions centered on the Bible; elements of Christianity, Judaism and other world religions; atheism and agnosticism; and religion and public life.

Pew has estimated in the past that Jews make up about 2.2 percent of the U.S. adult population and Muslims about 1.1 percent. But the survey found that more than half of Americans surveyed are not sure of the U.S. population size of those faith groups. Just one-quarter of U.S. adults correctly said Muslims comprise less than 5 percent of the population, and 19 percent correctly said Jews account for less than 5 percent of the population. Three in 10 overestimate the percentage of U.S. adults who are Jewish or Muslim.

Slightly more than a quarter of Americans surveyed answered the sole question about the U.S. Constitution correctly, saying there is no “religious test” or requirement to embrace a particular belief or religion to hold public office.

The survey, which drew on the expertise of Boston University scholar Stephen Prothero, the author of Religious Literacy, is not a definitive, course-like test on religion but rather a snapshot of knowledge about certain topics, Mr. Smith said.

Jews, atheists and agnostics scored highest—with each getting answers correct more than half of the time. Evangelical Protestants also had high scores compared with other groups.

There are a number of factors linked to people’s religious knowledge, from their education—both in academic and religious settings—to the range of individuals with whom they may socialize.

“Respondents who know other people from a wide variety of religious backgrounds tend to perform better on the survey’s questions about religious knowledge as compared with those who don’t know people from such a wide variety of religious backgrounds,” Mr. Smith said.

60 percent of Americans feel “warmly” toward Catholics

Researchers found that those who answered more questions correctly are generally more likely to feel warmly toward people of other faiths.

Jews, atheists and agnostics scored highest—with each getting answers correct more than half of the time.

Jews were viewed most warmly overall, with a “mean thermostat rating” of 63 on a scale of 0 to 100. Atheists and Muslims tied for the lowest point on that scale, with a rating of 49. Catholics received a rating of 60, the same as mainline Protestants. Evangelical Protestants fared a bit lower, at 56.

Buddhists, Jews, Hindus, atheists and mainline Protestants tended to get significantly warmer ratings from those who did well on the religious knowledge survey, and Catholics got slightly warmer ratings from the religiously knowledgeable.

Protestant evangelicals were the exception to the rule, Mr. Smith said. Evangelicals had an average thermometer rating of 53 among those who answered eight or fewer questions correctly, but their rating dropped to 43 among those who got 25 to 32 answers right.

On average, Catholics are about average in their religious knowledge

Overall, the average respondent answered 14.2 of the 32 quiz questions correctly. Among Catholics, the average score was 14.0. With an average score of 13.9, Mormons were also close to the overall score.

Catholics responded correctly to an average 7.9 out of the 14 questions specifically on the Bible and Christianity and 4 of the 13 questions on specific aspects of other world religions.

Jewish respondents did the best, on average correctly answering 18.7 of the 32 questions. Atheists got an average score of 17.9. The lowest scores were among members of historically black Protestant churches (9.7) and those who said they were “nothing in particular” (11.4).

The survey found that Christians who attended a religious school growing up did better on answering questions about their own religion, and even those who had religious education such as C.C.D. classes did better than those who had no such religious education.

Pew’s report includes an opportunity for readers to test their own religious knowledge with an interactive quiz.

The survey, conducted Feb. 4-19, had an overall margin of error of plus or minus 1.5 percentage points.

Other findings, on average:

  • Male respondents answered more questions correctly than women (15.5 compared with 13.0).
  • Whites got more questions right (15.4) than Hispanics (11.7) and blacks (10.5).
  • Americans 65 and older answered 16 questions correctly, compared with those under 30, who got 11.9 right.

Additional reporting by Robert David Sullivan.