Sometimes dumb sounds cute: Sixty percent of Americans can't name five of the Ten Commandments, and 50% of high school seniors think Sodom and Gomorrah were married.
Stephen Prothero, chairman of the religion department at Boston University, isn't laughing. Americans' deep ignorance of world religions - their own, their neighbors' or the combatants in Iraq, Darfur or Kashmir - is dangerous, he says.
His new book, Religious Literacy: What Every American Needs to Know - and Doesn't, argues that everyone needs to grasp Bible basics, as well as the core beliefs, stories, symbols and heroes of other faiths.
Belief is not his business, says Prothero, who grew up Episcopalian and now says he's a spiritually "confused Christian." He says his argument is for empowered citizenship.
"More and more of our national and international questions are religiously inflected," he says, citing President Bush's speeches laden with biblical references and the furor when the first Muslim member of Congress chose to be sworn in with his right hand on Thomas Jefferson's Quran.