The secret of Nobel Peace Laureate Mother Teresa was revealed in the book Iconic Nun's Letters by Rev. Brian Kolodiejchuk, the priest who's making the case to the Vatican for Mother Teresa's proposed sainthood.:
In a new book that compiles letters she wrote to friends, superiors and confessors, her doubts are obvious.
Shortly after beginning work in Calcutta's slums, the spirit left Mother Teresa.
"Where is my faith?" she wrote. "Even deep down… there is nothing but emptiness and darkness... If there be God — please forgive me."
Eight years later, she was still looking to reclaim her lost faith.
"Such deep longing for God… Repulsed, empty, no faith, no love, no zeal," she said.As her fame increased, her faith refused to return. Her smile, she said, was a mask.
"What do I labor for?" she asked in one letter. "If there be no God, there can be no soul. If there be no soul then, Jesus, You also are not true." [...]
According to her letters, Mother Teresa died with her doubts. She had even stopped praying, she once said.
Source: CBS