The first amendment of the United States Constitution forbids state-sanctioned religion, yet guarantees the right to its expression: "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof." Today, certain groups seem eager to promote nonsense in public education derived (openly or not) from their beliefs, whereas others argue that religion itself consists of nothing but nonsense. Herein lies a conflict: given these competing interests, how do we implement a constitutional mandate enabling both freedom from and to religion?

According to the Discovery Institute, a Seattle-based think-tank with a long history of support for creationism, "open discussion in science is under growing attack by the Darwin lobby." Modern creationists have championed many cases of alleged persecution at the hands of the "Darwin lobby," arguing that leftist academics are purging the ranks of schools and workplaces alike. One such example publicized by the Discovery Institute concerned Minnesota high school teacher Rodney LeVake. Because he refused to accurately cover evolution in his biology class, his district reassigned him the following year. His suit to regain his status in biology, claiming "academic freedom," was found to be baseless by the courts. They recognized that Mr. LeVake's right to his opinion did not entitle him to misrepresent a state-mandated curriculum.

I'm a paleontologist, and scientists like me have been scouring the Earth's outcrops for decades. Among other discoveries, we consistently find primates in the Eocene, but not apes. We find mammals in the Jurassic, but not primates. We find amniotes in the Carboniferous, but not mammals, and so on. Why? Because they hadn't yet evolved. The sequence of life forms present in geological deposits representing the past half-billion years is one of many lines of evidence in support of evolution. Darwin knew relatively little about this sequence, yet his theory made specific predictions about what later scientists would find. The evolutionary tree of life implies that the oldest representatives of large groups (e.g., mammals) existed earlier in time than those of smaller groups (e.g., apes). The tree of vertebrate life based on comparative anatomy fits very well with the sequence of the fossil record, not to mention other data like development and DNA. For Darwin to have articulated a mechanism by which multiple lines of evidence are expected, and found, to correspond shows that he was right.

Teachers do not have the "academic freedom" to distort this evidence, for example by stating that animals since the Cambrian show "very little change throughout the rock layers," as Mr. LeVake did in a 2008 interview with the Discovery Institute. A civil society cannot force him to reject belief in static species, custom-designed by a human-like god who circumvents natural processes. However, because his job required knowledge of history and science, his beliefs on those topics should not be insulated from scrutiny by his employer. There is a clear, historical link between creationist objections to evolutionary theory and religiously motivated incursions into school curricula. The U.S. Constitution in such cases has served the public well by requiring a "legitimate secular purpose" for topics mandated in science class.

But now consider the eagerness of some atheists to deny that religion has any redeeming value, who argue that belief in a 6,000-year-old Earth is just as absurd as belief in God. Some even label those who attempt to reconcile religion with science as creationists ourselves. Never mind that the winning side of major U.S. court decisions supporting evolution in public schools has regularly featured experts who recognize compatibility between science and religion. If they are "creationists," then so was Charles Darwin.

Real creationism, the kind that was judged to violate the establishment clause by state or Supreme courts in 1968, 1981, 1987 and 2005, can be ruled out by science because it defies a lot of what we know about Earth history. However, it is not "creation" itself that conflicts with science, but the implication of certain processes (involving for example a ridiculously short period of time) by which this "creation" took place. Asserting that a deity is behind a given process leaves the material basis for that process completely open to further investigation. Analogously, regarding Thomas Edison as the inventor of the light bulb says nothing about how it actually works, and no reasonable person would conclude his non-existence from our understanding of electricity. In other words, understanding a natural mechanism is generally independent of a potential agency behind it.

The U.S. constitution was written by individuals who viewed nature and its laws as consistent with the existence of a deity. I too believe in God, and am grateful to the framers for crafting a system by which religious beliefs cannot be legislated. Yet this constitutional assurance is double-edged because it seeks to balance the protection of society from popular superstition with each individual's right to religious expression. This balance lends itself to one of the most pressing issues of our society today: distinguishing superstition from religion, and ensuring that the right to believe does not cripple an understanding of our planet and ourselves.