L'Oreal Paris' Ninth Annual Women Of Worth CelebrationDiane Keaton has found Jesus — in HBO's upcoming "The Young Pope."

The cable network announced that the Oscar-winning actress is joining the cast of the drama as Sister Mary, an American nun living in the Vatican City. She'll star opposite Jude Law, who plays Pius XIII, born Lenny Belardo, who is the first American to be elected pope and who becomes the most conservative leader the Catholic Church has ever seen.

Sister Mary raised Lenny, helped him get elected, and continues to have power over him. Pius XIII is also described as "a man of great power who's stubbornly resistant to the Vatican courtiers, unconcerned with the implications for his authority."

This marks Keaton's first-ever series regular television role. Creator and Oscar winner Paolo Sorrentino ("Great Beauty") will direct all eight episodes of "The Young Pope," which begins filming soon.

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