As a physicist, I do a lot of writing and public speaking about the remarkable nature of our cosmos, primarily because I think science is a key part of our cultural heritage and needs to be shared more broadly. Sometimes, I refer to the fact that religion and science are often in conflict; from time to time, I ridicule religious dogma. When I do, I sometimes get accused in public of being a “militant atheist.” Even a surprising number of my colleagues politely ask if it wouldn’t be better to avoid alienating religious people. Shouldn’t we respect religious sensibilities, masking potential conflicts and building common ground with religious groups so as to create a better, more equitable world?

I found myself thinking about those questions this week as I followed the story of Kim Davis, the county clerk in Kentucky who directly disobeyed a federal judge’s order to issue marriage licenses to gay couples, and, as a result, was jailed for contempt of court. (She was released earlier today.) Davis’s supporters, including the Kentucky senator and Presidential candidate Rand Paul, are protesting what they believe to be an affront to her religious freedom. It is “absurd to put someone in jail for exercising their religious liberties,” Paul said, on CNN.

The Kim Davis story raises a basic question: To what extent should we allow people to break the law if their religious views are in conflict with it? It’s possible to take that question to an extreme that even Senator Paul might find absurd: imagine, for example, a jihadist whose interpretation of the Koran suggested that he should be allowed to behead infidels and apostates. Should he be allowed to break the law? Or—to consider a less extreme case—imagine an Islamic-fundamentalist county clerk who would not let unmarried men and women enter the courthouse together, or grant marriage licenses to unveiled women. For Rand Paul, what separates these cases from Kim Davis’s? The biggest difference, I suspect, is that Senator Paul agrees with Kim Davis’s religious views but disagrees with those of the hypothetical Islamic fundamentalist.

The problem, obviously, is that what is sacred to one person can be meaningless (or repugnant) to another. That’s one of the reasons why a modern secular society generally legislates against actions, not ideas. No idea or belief should be illegal; conversely, no idea should be so sacred that it legally justifies actions that would otherwise be illegal. Davis is free to believe whatever she wants, just as the jihadist is free to believe whatever he wants; in both cases, the law constrains not what they believe but what they do.

In recent years, this territory has grown murkier. Under the banner of religious freedom, individuals, states, and even—in the case of Hobby Lobby—corporations have been arguing that they should be exempt from the law on religious grounds. (The laws from which they wish to claim exemption do not focus on religion; instead, they have to do with ((Often,%20the laws from which they wish to claim exemption have to do with social issues, such as abortion and gay marriage.)), such as abortion and gay marriage.) The government has a compelling interest in insuring that all citizens are treated equally. But “religious freedom” advocates argue that religious ideals should be elevated above all others as a rationale for action. In a secular society, this is inappropriate.

The Kim Davis controversy exists because, as a culture, we have elevated respect for religious sensibilities to an inappropriate level that makes society less free, not more. Religious liberty should mean that no set of religious ideals are treated differently from other ideals. Laws should not be enacted whose sole purpose is to denigrate them, but, by the same token, the law shouldn’t elevate them, either.

In science, of course, the very word “sacred” is profane. No ideas, religious or otherwise, get a free pass. The notion that some idea or concept is beyond question or attack is anathema to the entire scientific undertaking. This commitment to open questioning is deeply tied to the fact that science is an atheistic enterprise. “My practice as a scientist is atheistic,” the biologist J.B.S. Haldane wrote, in 1934. “That is to say, when I set up an experiment I assume that no god, angel, or devil is going to interfere with its course and this assumption has been justified by such success as I have achieved in my professional career.” It’s ironic, really, that so many people are fixated on the relationship between science and religion: basically, there isn’t one. In my more than thirty years as a practicing physicist, I have never heard the word “God” mentioned in a scientific meeting. Belief or nonbelief in God is irrelevant to our understanding of the workings of nature—just as it’s irrelevant to the question of whether or not citizens are obligated to follow the law.

Because science holds that no idea is sacred, it’s inevitable that it draws people away from religion. The more we learn about the workings of the universe, the more purposeless it seems. Scientists have an obligation not to lie about the natural world. Even so, to avoid offense, they sometimes misleadingly imply that today’s discoveries exist in easy harmony with preëxisting religious doctrines, or remain silent rather than pointing out contradictions between science and religious doctrine. It’s a strange inconsistency, since scientists often happily disagree with other kinds of beliefs. Astronomers have no problem ridiculing the claims of astrologists, even though a significant fraction of the public believes these claims. Doctors have no problem condemning the actions of anti-vaccine activists who endanger children. And yet, for reasons of decorum, many scientists worry that ridiculing certain religious claims alienates the public from science. When they do so, they are being condescending at best and hypocritical at worst.

This reticence can have significant consequences. Consider the example of Planned Parenthood. Lawmakers are calling for a government shutdown unless federal funds for Planned Parenthood are stripped from spending bills for the fiscal year starting October 1st. Why? Because Planned Parenthood provides fetal tissue samples from abortions to scientific researchers hoping to cure diseases, from Alzheimer’s to cancer. (Storing and safeguarding that tissue requires resources, and Planned Parenthood charges researchers for the costs.) It’s clear that many of the people protesting Planned Parenthood are opposed to abortion on religious grounds and are, to varying degrees, anti-science. Should this cause scientists to clam up at the risk of further offending or alienating them? Or should we speak out loudly to point out that, independent of one’s beliefs about what is sacred, this tissue would otherwise be thrown away, even though it could help improve and save lives?

Ultimately, when we hesitate to openly question beliefs because we don’t want to risk offense, questioning itself becomes taboo. It is here that the imperative for scientists to speak out seems to me to be most urgent. As a result of speaking out on issues of science and religion, I have heard from many young people about the shame and ostracism they experience after merely questioning their family’s faith. Sometimes, they find themselves denied rights and privileges because their actions confront the faith of others. Scientists need to be prepared to demonstrate by example that questioning perceived truth, especially “sacred truth,” is an essential part of living in a free country.

I see a direct link, in short, between the ethics that guide science and those that guide civic life. Cosmology, my specialty, may appear to be far removed from Kim Davis’s refusal to grant marriage licenses to gay couples, but in fact the same values apply in both realms. Whenever scientific claims are presented as unquestionable, they undermine science. Similarly, when religious actions or claims about sanctity can be made with impunity in our society, we undermine the very basis of modern secular democracy. We owe it to ourselves and to our children not to give a free pass to governments—totalitarian, theocratic, or democratic—that endorse, encourage, enforce, or otherwise legitimize the suppression of open questioning in order to protect ideas that are considered “sacred.” Five hundred years of science have liberated humanity from the shackles of enforced ignorance. We should celebrate this openly and enthusiastically, regardless of whom it may offend.

If that is what causes someone to be called a militant atheist, then no scientist should be ashamed of the label.