Finger Feud: Langella?s Nixon gets straight to the point.

Sister Aloysius Beauvier will give you nightmares. The nun, half of the battle between good and evil, old and new, terrifying and friendly in John Patrick Shanley’s Doubt, will make you hold your breath as she silently paces a classroom, snap your shoulders back when she tells a young churchgoer to “Straighten up!” in more hiss than whisper, and pity the student she calls to from across the schoolyard with a simple but furious “Boy!”

Sister Aloysius is played by Meryl Streep, and it doesn’t matter if you’ve spent the summer going to Mamma Mia! singalongs, giddily warbling with the curly-haired, overalls-wearin’, contagiously blissful Academy Award winner. It may not even matter if you’ve attended parochial school. Streep’s holy woman is a beast in a habit of the very accurate throwback variety, and she will put the fear of God in you.

Though Streep’s performance is fierce, it’s not the only good reason to see Doubt, which Shanley both directed and adapted from his Pulitzer- and Tony-winning play. Doubt’s story is set in 1964 at a Bronx Catholic school just starting to feel the clash between members of the traditional religious order, represented by Sister Aloysius as well as the ancient nuns she both scolds and protects, and the younger punks unshackled by Vatican II, such as kindly history teacher Sister James (Amy Adams, again well-cast as a gentle ray of light) and the new parish priest, Father Flynn (Philip Seymour Hoffman).

Father Flynn is warm, easily connecting with his flock thanks to a ready smile and homilies that are both compellingly delivered and actually thought-provoking—not exactly what most churchgoers are accustomed to tuning out every Sunday. (Shanley expertly contrasts the unexpected intimacy of a Flynn Mass with Doubt’s opening shots: Outside the church, it’s cold and gray, and even inside the sacristy is cramped and dark as altar boys prepare incense that will virtually choke anyone who’s spent a panicked youth inhaling it.) Flynn doesn’t seem to view her as much of a threat, merely a relic of the church’s old and soon-to-be-bygone days. While she and the rest of the convent eat dinner in silence, with libations no stronger than milk, Flynn and his fellow priests are shown telling jokes over booze, their faces red from both.

Flynn stops regarding Sister Aloysius as a bitter old broad, however, not long after her persistent badgering of Sister James to be more vigilant with her classroom leads the young nun to confide something she thought odd: One afternoon, Father Flynn called one of Sister James’ students, Donald (Joseph Foster II), to the rectory. Donald acted strangely when he returned and had alcohol on his breath. Sister Aloysius needs only this information and a short meeting in which she notices some of Father Flynn’s mundane preferences (sugar in his tea, modern pen, fondness for secular Christmas songs) to come to an unshakable conclusion: Three lumps + ballpoint + “Frosty the Snowman” = pedophile.

The plot of Doubt, first staged in 2004, was obviously inspired by news of church coverups regarding molestation of children by its priests. There’s no question what Sisters Aloysius and James are thinking when Donald’s behavior that day is first brought up, yet the offense itself is never stated—euphemisms such as “terrible thing” and “welfare of children” are used instead, even until the movie’s end. Shanley uses the allegation more as a launchpad to address issues of trust, trade-offs (Donald’s mother, played by a steely but aching Viola Davis, has a surprising reaction to the suspicions), and the ugliness that can grow around an unsubstantiated rumor. The changes brought by Vatican II and the ’60s in general are also scrutinized: Is it better for teachers, priests, and parents to come off as feared authority figures or as permissive friends?

Doubt unsurprisingly turns into a Hoffman–Streep throwdown. Both Serious Actors deliver passionate performances, though Hoffman is less showy and less likely to grab as much attention as his costar. It’s become wearying to hear people cry “Oscar!” whenever Streep takes a role, and her workhorse predictability could turn viewers off of her theatrical turn here. But Catholic-school survivors will know: When Sister Aloysius is at her most apoplectic, yelling, “I may not have proof, but I have my certainty!” as she points in that very nunlike way to the ceiling and then her chest, it’s an award-winning moment.