The highly entertaining sci-fi flick I Am Legend stars Will Smith as the last man left in New York City (and maybe on earth) after a cure for cancer mutates into a virus that kills 90 percent of the population and turns 99 percent of the remnant into flesh-eating zombies, is likely to be the big winner at the Christmas box office. Those who enjoy tracking blockbusters more for their allegory than their grosses, though, may relish the movie’s timing because of its surprising subtext about how religion and science can co-exist.

Call this the first movie of the post-stem cell-debate era. After last month’s wonderful news that genetically matched stem cells could be developed without embryos, liberals were flummoxed (and maybe angered) by the news that, when it comes to medical ethics and science, Bush-era America actually could walk and chew gum at the same time. No embryos means no embryo destruction, therefore no moral problems with the stem-cell research of the future.

Smith plays a soldier/scientist immune to the virus that has destroyed humanity and turned Manhattan into a postapocalyptic wasteland where deer and other wildlife run free but there is no sign of another human being. In a twist on the grimy despair of last year’s similar Children of Men, Smith’s character has hopes of using his own blood to concoct a serum that will reverse the effects of the virus and turn the zombies back into ordinary people. He’s an atheist who believes that science, and science alone, holds the key to the future. But in a third-act twist, it turns out that religion and blind faith will have equally important roles to play if there is to be a cure–you might also use the word “salvation”–for humanity.