Every two years the National Science Foundation produces a report, Science and Engineering Indicators, designed to probe the public’s understanding of science concepts. And every two years we relearn the sad fact that U.S. adults are less willing to accept evolution and the big bang as factual than adults in other industrial countries.

Except for this time. Was there suddenly a quantum leap in U.S. science literacy? Sadly, no. Rather the National Science Board, which oversees the foundation, chose to leave the section that discussed these issues out of the 2010 edition, claiming the questions were “flawed indicators of scientific knowledge because responses conflated knowledge and beliefs.” In short, if their religious beliefs require respondents to discard scientific facts, the board doesn’t think it appropriate to expose that truth.

The section does exist, however, and Science magazine obtained it. When presented with the statement “human beings, as we know them today, developed from earlier species of animals,” just 45 percent of respondents indicated “true.” Compare this figure with the affirmative percentages in Japan (78), Europe (70), China (69) and South Korea (64). Only 33 percent of Americans agreed that “the universe began with a big explosion.”

Consider the results of a 2009 Pew Survey: 31 percent of U.S. adults believe “humans and other living things have existed in their present form since the beginning of time.” (So much for dogs, horses or H1N1 flu.) The survey’s most enlightening aspect was its categorization of responses by levels of religious activity, which suggests that the most devout are on average least willing to accept the evidence of reality. White evangelical Protestants have the highest denial rate (55 percent), closely followed by the group across all religions who attend services on average at least once a week (49 percent).

I don’t know which is more dangerous, that religious beliefs force some people to choose between knowledge and myth or that pointing out how religion can purvey ignorance is taboo. To do so risks being branded as intolerant of religion. The kindly Dalai Lama, in a recent New York Times editorial, juxtaposed the statement that “radical atheists issue blanket condemnations of those who hold religious beliefs” with his censure of the extremist intolerance, murderous actions and religious hatred in the Middle East. Aside from the distinction between questioning beliefs and beheading or bombing people, the “radical atheists” in question rarely condemn individuals but rather actions and ideas that deserve to be challenged.

Surprisingly, the strongest reticence to speak out often comes from those who should be most worried about silence. Last May I attended a conference on science and public policy at which a representative of the Vatican’s Pontifical Academy of Sciences gave a keynote address. When I questioned how he reconciled his own reasonable views about science with the sometimes absurd and unjust activities of the Church—from false claims about condoms and AIDS in Africa to pedophilia among the clergy—I was denounced by one speaker after another for my intolerance.

Religious leaders need to be held accountable for their ideas. In my state of Arizona, Sister Margaret McBride, a senior administrator at St. Joseph’s Hospital in Phoenix, recently authorized a legal abortion to save the life of a 27-year-old mother of four who was 11 weeks pregnant and suffering from severe complications of pulmonary hypertension; she made that decision after consultation with the mother’s family, her doctors and the local ethics committee. Yet the bishop of Phoenix, Thomas Olm­sted, immediately excommunicated Sister Margaret, saying, “The mother’s life cannot be preferred over the child’s.” Ordinarily, a man who would callously let a woman die and orphan her children would be called a monster; this should not change just because he is a cleric.

In the race for Alabama governor, an advertisement bankrolled by the state teachers’ union attacked candidate Bradley Byrne because he supposedly supported teaching evolution. Byrne, worried about his political future, felt it necessary to deny the charge.

Keeping religion immune from criticism is both unwarranted and dangerous. Unless we are willing to expose religious irrationality whenever it arises, we will encourage irrational public policy and promote ignorance over education for our children.