I can't imagine there's an adult out there who doesn't know Mother Teresa, the inimitable humanitarian and recipient of the 1979 Nobel Peace Prize for her endless charitable work caring for, comforting, and loving the sick and poor. Regardless of one's faith (or absence of), Mother Teresa — full name Blessed Teresa of Calcutta, MC — is universally admired for her compassion and kindness, particularly for the underprivileged.

Many folks know Mother Teresa was a Roman Catholic nun and missionary who founded the Missionaries of Charity, a religious congregation that caters to the poor in more than 133 countries. Many may also know that after multiple illnesses, Mother Teresa died in 1997 and that soon after her death, the process of beatification and canonization began to have her named as a saint.

THE LETTERS, a compelling drama about Mother Teresa's life, is based on documents...