On May 15, 1997, Mother Teresa greets people at the Missionaries of Charity for Destitute Children in New Delhi. Pope Francis has recognized a second miracle attributed to the late nun, clearing the path for her to be elevated to sainthood next year. (Ravi Raveendran/AFP/Getty Images)

The Vatican announced Friday that Pope Francis will canonize Mother Teresa, perhaps the most famous Catholic sister in modern times. She will, perhaps in several months, become known as St. Teresa of Calcutta (or Kolkata). Though she died almost 20 years ago, her name is still synonymous for many with charity, and the habit of blue-and-white saris that the women’s branch of her order wears is still familiar to millions.

But what many don’t know about this soon-to-be saint is that she spent the final decades of her life feeling an almost complete absence of God.

When she was in her mid-30s, she experienced a rare spiritual grace: actually hearing the voice of God. This prompted her to devote her entire life to the “poorest of the poor.” But just a few years later, that closeness to God evaporated almost entirely.

For the following decades, until her death at age 87, she worked with the poor, founded a religious order and traveled around the world preaching God’s love, without any interior experience of God’s presence. It is this fidelity to her original call, this willingness to carry out her ministry without any inner spiritual support, that I believe makes her the greatest saint of modern times.

[Pope Francis attributes second miracle to Mother Teresa, paving the way for sainthood]

The announcement of the canonization follows the Vatican’s report Thursday that a healing in 2008 of a Brazilian man from a viral brain infection has been declared by medical officials to be “inexplicable in the light of present-day medical knowledge.” About to enter into surgery, the man, comatose, suddenly woke up and said, “What am I doing here?” At the time of his recovery, his wife had been praying in a church, asking for Mother Teresa’s prayers. Afterward, he was found to be asymptomatic.

Born Anjezë (Agnes) Gonxhe Bojaxhiu in Albania in 1910, the woman who would become known as Mother Teresa entered the Sisters of Loretto, and was sent to teach in India in 1929. After two decades of teaching, while on a train ride from Calcutta to Darjeeling for a rest, she had a series of mystical experience in which she heard the voice of Jesus. Most saints experience a closeness with God, and a few have experienced “visions,” but what are called “locutions” are very rare. In Mother Teresa’s case, she reported that the voice of Jesus asked her to leave behind her teaching and plunge into ministry with the very poor. Afterward, for a time, she felt a deep closeness with him.

In 1948 she left the Sisters of Loretto and began her work in the slums, eventually founding the Missionaries of Charity.

Then something even rarer occurred: her interior life dried up completely. A few years after her experience on the train, God began to feel distant, then absent. She wrote to her spiritual director, “In my soul I feel just that terrible pain of loss, of God not wanting me, of God not being God, of God not really existing.”

That painful feeling of absence, what spiritual writers call a “dark night,” lasted until her death and was not discovered by the general public until her collected letters, titled “Come, Be My Light,” were published in 2007.

The publication shocked many. Some falsely concluded that she no longer believed in God. But there is a difference between not feeling God’s presence and not believing in God. (If I don’t hear from a friend for years, I may start to doubt his or her love. I need not doubt his or her existence.) And while an extended dark night is rare, shorter periods of dryness are very common in the spiritual life, even in the lives of saints.

In time, Mother Teresa began to understand these feeling of God’s absence as a way of identifying with Jesus’s feelings of abandonment on the cross and also as a way of entering more deeply into union with the poor, who also often feel abandoned.

For decades, then, Mother Teresa remained faithful to her original call. Unlike almost any other saint, she carried out her ministry without the benefit of a warm and sustaining prayer life. This makes her already remarkable ministry among the poor even more extraordinary. She did it, as it were, on an empty tank of gas, running on the fumes of her earlier mystical experience.

It was an extraordinary act of fidelity, unparalleled as far as I know in the lives of the saints. For this reason alone I consider her the greatest saint of our time.

Saint Teresa of Calcutta, pray for us.

The Rev. James Martin is a Jesuit priest, editor-at-large of the Catholic news site America, and author of “My Life with the Saints” and a new novel, “The Abbey,” about a woman’s spiritual doubts.

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