Mother Theresa's dark secret life at News Forum

A reveal-all book, serialized in TIME Magazine and CBS, explores the inner thoughts of Mother Theresa in complex letters in which she doubts the religion she was so publicly attached to.

The book Mother Theresa: Come be my light publishes years of correspondence and letters between Mother Theresa and her spiritual guide, Rev. Michael Van Der Peet, TIME reported. She had requested that the controversial letters are destroyed but church officials had refused.

Shortly after beginning work in Calcutta's slums, Mother Theresa had an emotional crisis of faith.

"Where is my faith?" she wrote in one of the letters. "Even deep down… there is nothing but emptiness and darkness... If there be God — please forgive me."

In another letter, dated eight years later, Mother Theresa seems still trying to get the grips on her faith.

"Such deep longing for God… Repulsed, empty, no faith, no love, no zeal," she wrote.

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."

The book alleges that although she puts a holy face in public, in the letters Mother Theresa talks of the "dryness," "darkness," "loneliness" and "torture" she is going through in her life.

In the letters she says her life is "hell" and at one point says it has driven her to doubt the existence of heaven and even of God. She is acutely aware of the discrepancy between her inner state and her public demeanor.

"The smile," she writes, is "a mask" or "a cloak that covers everything."

"These are letters that were kept in the archbishop's house," the Rev. Brian Kolodiejchuk told CBS News.

The letters were gathered by Rev. Kolodiejchuk, the priest who's making the case to the Vatican for Mother Teresa's proposed sainthood. He said her obvious spiritual torment actually helps her case.

"Now we have this new understanding, this new window into her interior life, and for me this seems to be the most heroic," said Rev. Kolodiejchuk.

According to her letters, Mother Teresa died with her doubts. She had even stopped praying, she writes in one of her letters.