If you're going to say the unsayable and stay charming while doing so, it helps to look more like Sarah Silverman than Andrew Dice Clay. Silverman, who presents herself as the world's naughtiest nice Jewish girl, has porcelain skin, a silky cascade of straight black hair, and a slightly devilish but still wholesome smile that beams like a headlight through the darkness of a concert hall; she's like the anti-shiksa Ali MacGraw. Silverman would be a singular talent even if she wasn't beautiful, but it would be foolish to deny that watching a stand-up comedian who resembles the world's sexiest art-history major toss off one-liners about porn stars, doo-doo, Nazis, and the politics of white people trying to cozy up to African Americans by calling them ''n-----s'' exerts its own nasty-cuddly-freaky appeal. Silverman makes her attractiveness relevant by delivering each scathing, oooo-did-she-really-say-that? joke as if it were a come-on. She's flirtatious in her outrage: a stand-up coquette.
At the start of Sarah Silverman: Jesus Is Magic, a concert film with musical numbers, she performs a catchy neo-'60s pop ditty about how excited she is to put on a show, and for all the intentional stupidity of the lyrics, her ironic eagerness is infectious. Then, on stage, she launches into the world according to Silverman. ''I was raped by a doctor,'' she says in a voice of confessional flatness. ''Which is so bittersweet for a Jewish girl.'' Score! Even in our politically incorrect times, that's the tasteless equivalent of shock and awe: a joke that tweaks, and detonates, two taboos at once. When she's on, Silverman, with her willingness to say anything, can be liberating: a bomb-tossing jester in the blasphemous-and-proud-of-it tradition of Lenny Bruce and Howard Stern.
For all her fearlessness and talent, though, there's a crucial way, in Jesus Is Magic, that she falls short of those artists. On the concert stage, Silverman drifts in a dreamy daze from one topic to the next, consciously parading and ridiculing her princessy narcissism. For her, the tragedy of 9/11 is that it was the day she learned her beloved soy chai latte had 900 calories. She sings to a group of retirement-home folks, ''You're gonna die soon!'' And so on. The trouble with narcissism as a comic theme is that it starts to hem in one's responses to the outside world. Silverman's racial humor gooses forbidden stereotypes yet never reaches beyond those stereotypes. African Americans, in her act, are little more than layabouts and threats. We never hear her experiences just the clichés that have floated into her brain. Ditto her feelings about sex. She's very funny when she describes blending jelly and fellatio and then worries that she's turning into her mother, but unlike, say, Richard Pryor or Margaret Cho, she leaves any true observations about sex or relationships off stage. The closest she comes to voicing a conviction of any kind is her rather creaky belief that Jews should refrain from buying German cars. In Jesus Is Magic, Sarah Silverman reveals her own head to be an intermittently hilarious place, but she'd do well to take a trip or two outside it.