Rome, Italy - For millions, Mother Teresa embodied what a "saintly" life should be, but the Catholic Church's move to canonize her has not been without controversy.
On October 19, 2003 at a ceremony in Rome, Pope John Paul II beatified the ethnic-Albanian, Macedonian-born nun who won worldwide admiration for her work among the destitute and the dying in the slums of Calcutta.
It marked the shortest beatification process in modern history, putting Mother Teresa just one step from being declared a saint.
The fast-tracking was made possible by John Paul's decision in 1999 - less than two years after Mother Teresa's death on September 5, 1997 at the age of 87 - to waive the required five-year waiting period after a candidate's death before a canonization cause can be opened.
Among those attending the beatification ceremony in St Peter's Square was Monica Besra, a young Indian woman who claimed in 1998 that her large stomach tumour vanished after praying to Mother Teresa.
Some doctors who had treated Besra claimed that instead of a cancer the woman had had a cyst which was eliminated through medical procedure.
But despite such objections, the Vatican in 2002 recognized the healing as a miracle, paving the way for beatification.
The same year, many Catholics were startled to discover that Mother Teresa's faith in God, thought to have supported her during decades of adversity, had often wavered.
The "hidden" side of the would-be saint emerged from an article published by the official postulator of her cause, Father Brian Kolodiejchuk - a Canadian priest who worked with Mother Teresa for more than two decades and who is the driving force behind her canonization process.
In 2007, Kolodiejchuk published a book containing excerpts of personal letters to superiors and confessors - missives Mother Teresa had wanted destroyed - in which she detailed her anguish and doubts.
"If there be God - please forgive me. When I try to raise my thoughts to Heaven, there is such convicting emptiness that those very thoughts return like sharp knives and hurt my very soul," she wrote in one letter.
Vatican officials have indicated that such revelations have not harmed her cause. On the contrary, they drew comparisons between her turmoil and that of many of the Catholic Church's most celebrated holy men and women.
What apparently remains a requirement for the completion of Mother Teresa's canonization, is the identification of another miracle.
With customary Vatican secrecy on such matters, officials are refusing to provide further details or the timeframe involved.
Some critics contend that the swiftness with which Mother Teresa's cause was handled may have benefited from John Paul II's enthusiasm to declare new saints.
The Polish-born pontiff, who died in 2005, approved some 1,340 beatifications and 482 canonizations - more than all his modern predecessors combined.
His successor, Pope Benedict XVI, has tightened the rules governing canonization processes.
Guidelines issued in 2008 by the Vatican's Congregation for the Causes of Saints, stressed the need to identify a "true reputation for holiness" among candidates for sainthood.
Bishops were also instructed to carry out thorough research before forwarding to Rome information on candidates originating from their dioceses.
Yet Mother Teresa remains a hugely popular choice for sainthood, and her admirers - Hindus, Sikhs and Muslims have joined Catholics in prayers held in Calcutta for her speedy canonization - vastly outnumber her detractors.
Benedict himself has declared his high esteem, citing her four times in his 2006 encyclical on social justice Deus Caritas Est (God is Love).
In the document, one of the most important of his pontificate, Benedict mentioned her as a "saint" even if she has yet to be canonized.
"The saints - consider the example of Blessed Teresa of Calcutta - constantly renewed their capacity for love of neighbour from their encounter with the Eucharistic Lord, and conversely this encounter acquired its realism and depth in their service to others.
Love of God and love of neighbour are thus inseparable, they form a single commandment," Benedict wrote.