Teachers at a Pennsylvania secondary school walked out of their classrooms in protest last week as their school became the first in America explicitly to endorse a Christian fundamentalist alternative to the theory of evolution.
The staff boycott forced officials of the education authority in Dover, Pennsylvania, to enforce its new edict requiring students to be "made aware" of the "intelligent design" belief, which holds that life sprang from the hands of an omniscient creator.
Evolution "is not a fact" students at Dover area high school were told.
"Gaps in the theory exist for which there is no evidence.Intelligent design is an explanation of life that differs from Darwin's view."
Science teachers refused to be party to the statement, waiting outside their classes while it was read, citing their "solemn responsibility to teach the truth," in a letter to administrators.
"Intelligent design is not science. Intelligent design is not biology.
Intelligent design is not an accepted scientific theory," they wrote.
But the clash last Tuesday and Wednesday, highlights the resurgent political clout of evangelical Christians. Emboldened by their role in President Bush's re-election, they are stepping up their opposition to a theory that cuts across biblical explanations of the inception of life.
Challenges to evolution's teaching are pending in Montana, South Carolina, Missouri, Mississippi and Alaska; and expected in Alabama and Oklahoma, among other states.
Last week, officials from an education authority in the southern state of Georgia voted to appeal against a court ruling that ordered them to remove disclaimers from biology textbooks that declared evolution "a theory, not a fact". Cobb County school chiefs said the stickers represented tolerance of different viewpoints, rather than an attempt to foist private religious beliefs on schools.
Creationism - the belief that God created the world - commands widespread support in America. Two-thirds of Americans polled by broadcaster CBS following November's US election supported the teaching of creationism in schools alongside evolution.
But scientists said the public was being misled by spin from opponents of evolution theory, not least the conflation of the everyday meaning of "theory" with its scientific definition.
"In colloquial usage,'theory' is something speculative or conjectural," said Glen Branch of the National Center for Science Education. "In science, it's an explanatory system that makes sense of observations and facts."
Lawrence Krauss, physics professor at Case Western Reserve university, said evolution was on a par with Newton's theory of gravity or Einstein's relativity theory among scientists.
"These theories are constantly being refined, but no one questions them," he added.
Ultimately it's a question of "academic integrity and lying," rather than separation of church and state in America's constitution or respecting religious sensibilities as the evolution debate is customarily framed, Mr Krauss said.
"Anti-evolution theory groups give the impression evolution is controversial or questionable, when neither is true."
Mr Branch said the rising tension over evolution is having a chilling effect on its teaching across US schools, with staff steering clear of what's become a politically-charged topic.