Letters revealing Mother Teresa’s half-century-long “crisis of faith” have many pondering what to make of the secret life of one of the most revered figures in modern history.

Yet as theologians and psychologists offer interpretations for her deep “darkness,” a preeminent American theologian used Mother Teresa’s struggle to remind believers to trust Christ and not their feelings.

Whether it be an average Christian or a saint, doubts on the existence of God and turmoil over the inability to feel His presence is something every Christian has wrestled with.

Yet more important than dwelling on human emotions is securing one’s faith in Christ, according to Dr. R. Albert Mohler, Jr., the president of The Southern Baptist Theological Seminary. The Southern Baptist Theological Seminary is the flagship school of the Southern Baptist Convention and is one of the largest seminaries in the world.

“Salvation comes to those who believe in Christ – it is by grace we are saved through faith,” wrote Mohler in an online column Thursday in “On Faith” – a project of The Washington Post and Newsweek magazine.

“But the faith that saves is not faith in faith, nor faith in our ability [to] maintain faith, but faith in Christ,” he emphasized. “Our confidence is in Christ, not in ourselves.”

Mohler was responding to this week’s TIME cover story which explores Mother Teresa’s inner struggles in light of a new book, Mother Teresa: Come Be My Light, which was made public for the first time letters covering a period of 66 years in which she questioned her beliefs and God.

In correspondents to her spiritual confidants, Mother Teresa laments on the “dryness,” “darkness,” “loneliness,” and “torture” she suffers with her inability to feel God’s presence.

A letter to Archbishop Ferdinand Perier in 1953, according to TIME, read: "Please pray specially for me that I may not spoil His work and that Our Lord may show Himself — for there is such terrible darkness within me, as if everything was dead. It has been like this more or less from the time I started 'the work.'"

Another letter in 1956 read: “Such deep longing for God – and…repulsed – empty – no faith – no love – no zeal. – [The saving of] Souls holds no attraction – Heaven means nothing – pray for me please that I keep smiling at Him in spite of everything.”

Mother Teresa also painfully shared her inability to pray saying she just “utter words” of Community prayers– a confession that came from a woman who once said the Christmas holiday should remind the world “that radiating joy is real” because Christ is everywhere.

Yet despite the “pain and darkness” in her soul, Mother Teresa served tirelessly among the outcasts, the dying and the most abject poor in India. She brought countless sick Indians to her center from slums and gutters to be treated and cared for under the banner of Christ’s love.

“The very essence of faith, you see, is believing even in the absence of evidence,” said Chuck Colson, founder and chairman of Prison Fellowship, in a column Wednesday in response to the TIME article. “And it is the only way we can know Christ.

Colson shared that he experienced his own darkness of soul when a few years back two of his three children were diagnosed with cancer.

“We can conclude rationally that God exists, that His Word is true, and that He has revealed Himself” Colson said. “But without that leap of faith, we will never know God personally or accept His will in Christ.”

It was in the late 1950s when Mother Teresa met a well-known theologian, the Rev. Joseph Neuner, who helped her accept the “darkness” she felt.

Neuner gave her three pieces of counsel – first, there was no human cure for what she had, so she shouldn’t feel personally guilty about it; second, feeling Jesus is not the only evidence of His presence, and the fact that she longed for God is a “sure sign” of his “hidden presence” in her life; and last, the feeling of absence was part of the “spiritual side” of her work for Jesus.

Mother Teresa responded to Neuner in 1961: “I can’t express in words – the gratitude I owe you for your kindness to me – for the first time in ….years – I have come to love the darkness – for I believe now that it is part of a very, very small part of Jesus’ darkness & pain on earth.”

She later wrote to Neuner, “I accept not in my feelings – but with my will, the Will of God – I accept his will,” according to TIME.

“So what do the letters of Mother Teresa reveal? For one, they reveal the true cost of discipleship,” commented Colson. “To follow Christ is to embrace suffering and the Cross. And, at times, to say with Jesus, ‘My God, my God, why did you abandon me?’”

Baptist seminary head Mohler said that although he would not “presume to read Mother Teresa’s heart or soul,” he concluded from her story that faith should not be placed on volatile emotions but rather solely in the unchanging God.

“There is a sweet and genuine emotional aspect to the Christian faith, and God made us emotional and feeling creations,” wrote Mohler. “But we cannot trust our feelings. Our faith is not anchored in our feelings, but in the facts of the Gospel.

“Our confidence is in Christ, not in ourselves. We are weak; He is strong. We fluctuate; He is constant. We cannot trust our feelings nor our emotional state. We trust in Christ. Those who come to Christ by faith are not kept unto Him by our faith, but by his faithfulness,” wrote Mohler.

The Catholic Church is considering whether or not to make Mother Teresa a saint and the letters were collected as supporting materials for the process.

Mother Teresa died in 1997, nearly two decades after receiving the Nobel Peace Prize in 1979.