Mark Rylance will play the leader of Catholics all over the world following his and Spielberg's (pictured below) work on Bridge Of Spies, a Cold War espionage thriller.
He was honoured at the Academy Awards after his performance.
The new film, The Kidnapping Of Edgardo Mortara, will tell the true story of a young Jewish boy who in the mid-19th Century was forcibly taken from his Italian parents to be raised as a Christian.
The screen play is set to show the struggle between the Catholic Church and modern Italy at that time in history, it caused wide spread controversy around the world.
Rylance, 56, will play Pope Pius IX, who refused to return the boy to his parents and director Spielberg is expected to begin filming in early 2017.
Mark Rylance will appear on screens again this year in Spielberg's interpretation of The BFG, where he plays Roald Dahl's friendly giant.
