ROME — For much of her life, she was known as the "living saint."

On Sunday, the eve of the 19th anniversary of her death, Mother Teresa's sanctity will be sealed with a canonization Mass led by Pope Francis at the Vatican's St. Peter's Square.

To her legion of steadfast admirers, the Nobel Peace Prize winner's ascendance to "sanctified" status may look as inevitable as it is justified.

But for a nun whose name has long been a byword for pious compassion, her canonization has been met with controversy.

Much of the criticism of Mother Teresa has focused on how her practice of Catholic devotion collided with the real needs of the impoverished people she set out to help. In the eyes of some, particularly in India, she put fame and piety before her mission of aid.

Among other critiques, she has been accused of offering stingy or substandard medical care; of proselytizing to her patients; of claiming virtue in suffering rather than trying to alleviate it; cozying up to dictators; and of promoting her efforts to a global media eager for heroes.