When Joshua Rowand, an 11th grader in Dover, pa., looks out from his high school, he can see the United Church of Christ across the street and the hills beyond it, reminding him of what he's been taught from childhood: that God's perfect creation culminated on the sixth day with the making of man in his image. Inside the school, he is taught that Homo sapiens evolved over millions of years from a series of predecessor species in an unbroken line of descent stretching back to the origins of life. The apparent contradiction between that message and the one he hopes someday to spread as a Christian missionary doesn't trouble him. The entire subject of evolution by natural selection is covered in two lessons in high-school biology. What kind of Christian would he be if his faith couldn't survive 90 minutes of exposure to Darwin?

But many Americans would rather not put their children to that test, including a majority on the Dover School Board, which last month voted to inform students of the existence of alternatives to Darwin's theory. Eighty years after the Scopes trial, in which a Tennessee high-school teacher was convicted of violating a state law against teaching evolution, Americans are still fighting the slur that they share an ancestry with apes. This time, though, the battle is being waged under a new banner--not the Book of Genesis, but "intelligent design," a critique of evolution couched in the language of science. And in this debate, both sides claim to be upholding the principle of free inquiry. Proponents of I.D., clustered around a Seattle think tank called the Discovery Institute, regard it as an overdue challenge to Darwinism's monopoly over scientific discourse. "To say, as Darwinians do, that everything has to be reduced to a chemical reaction is more ideology than science," asserts Discovery's John West. Opponents, led by the Oakland, Calif.-based National Center for Science Education, regard I.D. as an assault on a basic principle of the Enlightenment, that science must explain nature through natural causes. "Intelligent design is predicated on a supernatural creator," says Vic Walczak, a lawyer with the American Civil Liberties Union, which is challenging Dover's introduction of the concept into biology classes. "That's not science, it's religion."

Walczak calls the Dover case, which has not yet come to trial, "Scopes Redux 25"-- the latest episode in the never-ending struggle to reconcile the Bible, Charles Darwin's "Origin of Species" and the First Amendment. The last round was touched off when the school board in suburban Cobb County, Ga., added stickers to its new biology textbooks warning students that "evolution is a theory, not a fact... [and] should be approached with an open mind, studied carefully and critically considered." "If you see that out of any context, you'd think it sounds reasonable," observes law professor Edward Larson, the leading historian of the Scopes trial and its aftermath. But the wording, he says, encourages confusion over the everyday meaning of "theory"--akin to "hunch"--with the scientific meaning, a systematic framework to explain observations. Evolution, which deals with events that no one was around to witness, will always be a "theory."

The other salient point about the sticker, Larson says, is that it singles out evolution for critical analysis, among all the potentially controversial views to which students might be exposed. Marjorie Rogers, the parent who led the campaign for the sticker, says her motives were purely to "expand the teaching of science in this area, and to correct bias and inaccuracy in the textbooks." But five other parents who didn't see it that way sued the board to remove the stickers. On Jan. 13, after a three-day trial, federal district court Judge Clarence Cooper ruled for the parents and ordered the stickers removed. Noting that Rogers "identifies herself as a six-day Biblical creationist," Cooper concluded that any "informed, reasonable observer" would know why the sticker was there, and "interpret [it] to convey a message of endorsement of religion." The board plans to appeal.

Ironically, this battle was touched off when Cobb County bought new textbooks --that actually covered evolution, after years in which the subject was largely ignored. The same kinds of struggles are cropping up in towns in Wisconsin, Arkansas and elsewhere, as school boards try to implement state curriculum standards mandated by Congress. All sides are keeping a close eye on Ohio, which last year adopted standards including an incendiary phrase about "critically analyz[ing] aspects of evolutionary theory." Kansas, which in the November election handed the anti-evolution forces a 6-4 majority on the state school board, is due to review its standards in February; five years ago, the state was widely ridiculed for eliminating evolution from the required curriculum entirely. The only thing lacking for a full-scale culture war is involvement by the national conservative movement, which has treated it as a local issue. That could change, though. Republican Sen. Rick Santorum of Pennsylvania, who wrote an op-ed article supporting the Dover School Board, says he regards evolution as one of the "big social issues of our time," along with abortion and gay marriage.

The Cobb County decision was a blow to the new tactic of attacking evolution with objective, scientific language. The Discovery Institute, which sent materials and offers of help to Cobb County but was not involved in drafting the sticker, takes pains to distinguish its critique of Darwinism from the Biblical fundamentalism espoused at the Institute for Creation Research, near San Diego. The view that the Earth was created by God within the past 12,000 years is thriving at the institute's museum, where school groups study murals of men cavorting with dinosaurs, before the beasts were wiped out by Noah's flood. The institute's vice president, Duane Gish, a biochemist, has managed to fit every observation from paleontology, astronomy and nuclear physics into a theory derived entirely from the Book of Genesis. The problem for Gish is that, although polls consistently show that nearly half of all Americans believe in the Biblical account, it has been a loser in the courts since 1987, when the Supreme Court (with Justice Antonin Scalia and Chief Justice William Rehnquist dissenting) struck down a Louisiana law calling for equal treatment of evolution and "creation science."

Soon thereafter, I.D. burst into public awareness with the publication of "Darwin on Trial" by Phillip Johnson, a Berkeley law professor who underwent a midlife conversion to evangelical Christianity. As a scientific theory, I.D. is making only slow progress in overcoming evolution's 150-year head start. Johnson and his followers seek to overturn two of the central precepts of evolution. The first is universal common descent, the idea that every living creature can trace an unbroken lineage back to the same primitive life forms, which arose billions of years ago from nonliving matter. Biologists, armed with the powerful tool of molecular genetics, overwhelmingly accept this view. Nevertheless, I.D. proponents are seeking to undermine it, mostly through popular books like "Icons of Evolution" by Jonathan Wells. Wells dissects some of the most famous textbook examples of evolution, such as the way peppered moths adapted a new color pattern for better camouflage after pollution killed the lichens on tree trunks. "There is a lot of ambiguity and dissent about the lines of evidence," insists Stephen Meyer, director of the Discovery Institute's Center for Science and Culture. "It's in the scientific literature, and we think students should know about it."

The second concept is natural selection, which holds that the entire complexity and ingenuity of life has evolved by the accumulation of small random mutations. Changes that help the organism survive in its environment, like the different shapes of the beaks Darwin observed on the birds of the Galapagos, are more likely to be passed on. Repeated over many generations, the process produces not just finches but naturalists to watch them. Many people have struggled with the philosophical implications of this theory, and entire disciplines of science are dedicated to working out its details. I.D. proposes an intuitively appealing alternative, that the living world reflects the design of a conscious, rational intelligence.

The classic illustration is the eye, which seems to depend on all its manifold parts working in concert. How, then, could it have arisen by a series of discrete steps? Evolutionary biologists respond that even a primitive light-sensitive spot has survival value, and have tried to show how a series of small improvements could eventually build the complete organ. With the publication of "Darwin's Black Box" in 1996, biochemist Michael Behe moved the argument to the cellular level, using examples such as the immune-system response. They exhibit what he calls "irreducible complexity," meaning that all their parts are necessary for them to function at all. This, he says, is the hallmark of intelligent design.

But I.D. has nothing to say on the identity of the designer or how he gets inside the cell to do his work. Does he create new species directly, or meddle with the DNA of living creatures? Behe envisions as one possibility something akin to a computer virus inserted in the genome of the first organism, emerging full-blown millions of generations later. Meyer's view is simply that "we don't know." He declines even to offer an opinion on whether people are descended from apes, on the ground that it's not his specialty. The diversity of life, in his view, is a "mystery" we may never solve.

For Eugenie Scott, executive director of the National Center for Science Education, there's no mystery about what I.D. proponents believe: "It's another way of saying God did it. It isn't a model of change; it isn't a theory that makes testable claims." A 2002 resolution by the American Association for the Advancement of Science called I.D. "an interesting philosophical or theological concept," but not one that should be taught in science classes. In fact, the Discovery Institute doesn't call for teaching I.D. in school either, only the "controversy" over Darwinism. But most scientists don't believe there is one. The institute's "Scientific Dissent From Darwinism," whose operative sentence reads "We are skeptical of claims for the ability of random mutation and natural selection to account for the complexity of life," has been signed by about 350 scientists. (AAAS has 120,000 members.) Scott's organization has circulated a countermanifesto asserting that "there is no serious scientific doubt that evolution occurred or that natural selection is [the] major mechanism... " As a tongue-in-cheek tribute to the late paleontologist Stephen Jay Gould, they signed up only scientists named Steve. At last count they had 528.

The real stakes, though, go beyond what high-school students are taught about Galapagos finches. To accept I.D. is to admit a supernatural process into the realm of science. In fact, that's just what I.D. proponents want to see happen, a revolution--or counterrevolution--against what Johnson calls "methodological naturalism." "Is it the obligation of the scientist to come up with a materialist explanation of phenomena, choosing among an artificially limited set of options," Meyer asks rhetorically, "or just the best explanation?"

Behe points out that while most Christians accept a God who set the universe in motion according to natural laws, evolution raises more difficult existential questions. People want to feel that God cares for them personally. British biologist Richard Dawkins has written that Darwin's theory "made it possible to be an intellectually fulfilled atheist." But that's not what most Americans want for their children. Margaret Evans, a psychologist at the University of Michigan, has studied religious beliefs in children and seen the appeal of creationism. "We are biased toward seeing the world as stable and purposeful," she says. "I don't know what to believe," one parent told her. "I just want my child to go to heaven."

Well, so does the pope, but the Vatican has said it finds no conflict between Christian faith and evolution. Neither does Francis Collins, the director of the Human Genome Institute at the National Institutes of Health and an outspoken evangelical. He wrote recently of his view that God, "who created the universe, chose the remarkable mechanism of evolution to create plants and animals of all sorts." It may require some metaphysical juggling, but if more people could take that view, there would be fewer conflicts like the one in Dover. In the debate over I.D., both sides acknowledge that most scientists accept evolution, but they agree that scientific disputes are not settled by majority vote. School-board elections, however, are.