CALCUTTA, India - Recent revelations about the crisis of faith suffered by Mother Teresa will not hamper her path to sainthood, her successor said Sunday at a ceremony to commemorate the 97th anniversary of her birth.

A new book set to be published in September contains letters written by Mother Teresa in which one of the world's best known religious figures describes how she felt alone and separated from God.

"I don't think it will have any effect on the process of sainthood for Mother Teresa," said Sister Nirmala, who succeeded Mother Teresa as the head of Missionaries of Charity, the organization she set up to help the poor of Calcutta.

The revelations about Mother Teresa's doubts with religion are not new. Her ordeal, described to a series of confessors and confidants, became public knowledge in 2003 during the investigation into whether she qualifies for sainthood, a process fast-tracked by Pope John Paul II.

But "Come Be My Light: The Private Writings of the 'Saint of Calcutta,'" to be released Sept. 4, collects her thoughts in one place for the first time, inviting a closer review of her life 10 years after her death.

"It is part of our Mother's spiritual life," Sister Nirmala said at the ceremony where hundreds of nuns and volunteers paid their respects by laying flowers and praying by her tomb.

"It is a path God chose for her deep interior purification and transformation," she said.

Mother Teresa was beatified in 2003. Under Catholic tradition, an additional miracle attributable to her must be verified for her to be elevated to sainthood.

The book was edited by the Rev. Brian Kolodiejchuk, a priest who knew Mother Teresa for 20 years and is the postulator for her sainthood cause. It depicts Mother Teresa as a mystic who experienced visions of Jesus speaking to her early in her ministry, only to lose that connection and long for it like an unrequited love for most of her last four decades.

"I have no Faith -- I dare not utter the words & thoughts that crowd in my heart -- & make me suffer untold agony," she wrote in an undated letter.

Mother Teresa, an ethnic Albanian who was born in what is now Macedonia, devoted her life to serving the poor in India and elsewhere. In 1929, she came to Calcutta where she later founded the Missionaries of Charity in 1950. She won the Nobel Peace Prize in 1979.