Meryl Streep, Philip Seymour Hoffman and Amy Adams hit the red carpet in Hollywood to premiere their new religious drama 'Doubt,' in theaters December 12 -- and ET spoke to the night's biggest stars!

Based on John Patrick Shanley's Pulitzer Prize-winning play, the drama unfolds in a Bronx Catholic school, circa 1964. Streep plays Sister Aloysius Beauvier, the iron-gloved school principal who rules through fear and discipline. Hoffman plays Father Flynn, a charismatic priest who is trying to loosen up the school's strict guidelines and customs.

"It's a great character and it's a wonderful piece the whole movie is so tightly plotted and beautifully realized," Streep says of the film. "I'm really proud of the movie. I hope everybody likes it."

But did the Academy Award winner have any trouble getting into the "habit" for the role?

"Just putting it on took me about half an hour," she joked.

When the school accepts its first black student, Sister James (Amy Adams) believes Flynn is paying too much personal attention to him. Soon, a battle of wills ensues as Beauvier embarks on a crusade to oust Flynn from the school.

Watch ET for more with the cast of 'Doubt'!