Listen to these words of one of the most admired Christians of the last hundred years:

Lord, my God, who am I that You should forsake me? The Child of Love—and now become as the most hated one—the one—You have thrown away as unwanted—unloved. I call, I cling, I want—and there is no One to answer–no One on Whom I can cling… Where is my Faith—even deep down right in there is nothing, but emptiness & darkness….

Those are the words of Mother Teresa of Calcutta, written several decades ago, and just published in a collection of her writings called Mother Teresa: Come Be My Light. Mother Teresa was, of course, the winner of the Nobel Peace Prize and someone revered as the model of self-sacrificing compassion because of her decades of ministry among the sick and dying on the streets of Calcutta. She has been admired not only for her remarkable work, but for the seeming depth and joy of her faith.

Now we have this book that details many years of spiritual despair and a sense of God’s absence and abandonment. Discussions about religion, already one of the hottest topics in America, heated up all over again over the last few weeks as atheists claimed her now as one of their own, and theologians hastened to put her experience in a broader spiritual context.

Clearly the publishing of these notes and letters has touched a nerve. Doesn’t faith require clear convictions? Can great believers have great doubts? What is religious faith anyway?

One problem is that the language of faith itself often seems to promise clarity. People hear in church talk of what God is “saying” to us, or “calling” us to do. Isn’t it our job to listen when God “speaks?” And prayer is often described as a conversation or dialogue, although many people I know grow weary of a conversation when it seems as if they are the only ones doing the talking.

And doesn’t it seem unfair that back in biblical days God seemed to speak clearly? “Sure,” I can imagine you saying, “Moses was a great hero leading the Jewish people to freedom. If I heard a voice speaking to me out of a burning bush I’d be a hero too.” And if I had been in the crowd around Jesus when a voice came down out of heaven declaring, “This is my Son, my Beloved; listen to him,” well, I think even I could get my act together and follow.

But things have changed. People don’t hear voices much any more, or if they do we either think they’re fooling us, or they need professional help. Now we read those old biblical stories with a sense that story and metaphor have enriched the way events from long ago have been remembered. In fact, my hunch is that one of the chief challenges for faith these days is the mystery of God’s seeming silence.

You may remember the film Love and Death, in which the Woody Allen character at one point turns his eyes toward heaven and says something like, “Give me an answer, God.” But nothing happens, and so he tries again. “Just a few words will be fine.” Again, only silence. Then he pleads, “How about at least a cough?” Allen taps into a hidden fear underneath prayer and the life of faith for many: Is anyone there? And I think it’s that fear and frustration that feeds our reluctance to pray and the cautiousness of our faith.

And so when we learn that maybe the most famous Christian of our time experienced long stretches of God’s absence, it gets our attention.

In 1946, after 17 years as a teacher in Calcutta with her order of nuns, Mother Teresa experienced an intense calling to give up teaching and to work in “the slums” of the city with “the poorest of the poor.” But soon after her work had begun she began to go through what she described as “dryness,” “darkness,” and “loneliness,” while all the while maintaining her publicly cheerful demeanor.

There was one brief period when her faith blossomed again, but it soon vanished. By 1961, with the help of a wise spiritual guide, she came to accept this emptiness and darkness as part of her own calling. “I have come to love the darkness—for I believe now that it is part, a very, very small part, of Jesus’ darkness and pain on earth.” As one Roman Catholic commentator puts it, “I’ve never read a saint’s life where the saint has such an intense spiritual darkness.”

Mother Teresa’s letters pull back the veneer of a seemingly perfect spiritual life, the kind we expect in our spiritual heroes, and in this case they show a very human woman called by Christ, and yet confused and devastated by how elusive her faith seemed to be.

Doubt, struggle, and the absence of God are nothing new for people of faith. The Psalms, which are the Bible’s Prayer Book, are full of complaints that God has deserted his people.

Lord, why have you cast me off, why do you hide your face from me?” (Psalm 88)

How long, Lord, will you hide yourself from my sight? (Psalm 89)

There are many references in the Old Testament to God “turning his back” on the Hebrew people, a way of speaking of God’s mysterious absence. And, of course, Jesus, hanging on the cross, seems to have experienced complete abandonment by God: “My God, my God, why have you forsaken me?” The great mystics such as John of the Cross believed that experiences of “night,” or darkness, or the absence of God are inevitable stages in the life of faith. We need them to help us let go of the small, inadequate images of God we keep concocting for ourselves.

John Wesley was perhaps the greatest Christian of 18th century England. In a time when the church had grown rigid and dry, Wesley traveled by horseback all over England preaching to miners and laborers in crowds of thousands, and breathing new life into the tired Church of England. Listen, though, to this letter to his brother Charles, written in a dark time:

And yet this is the mystery, I do not love God. I never did… Therefore I never believed in the Christian sense of the word. Therefore I am only an honest heathen,… And yet to be so employed of God!… I am borne along, I know not how, that I can’t stand still…

Wesley’s life was a muddle of mistakes, unhappy marriages, terrible misjudgments, of dark nights of the spirit. But he proved to be the greatest witness to Jesus Christ of his century. Maybe knowing and loving God isn’t about a clear, neat package of beliefs, unstoppable faith, and flawless achievements.

In fact, the journey of faith takes us through the terrain of mystery, of times of clarity and confusion, of presence and absence. God is the incomprehensible one, the vast presence inside and outside us, who holds all existence in being, and who can’t be captured in our images and ideas. We are in God as fish are in water. We can no more analyze God than a fish can the ocean. As St. Augustine put it, “If you understand, it is not God.” God will always be elusive.

Faith is an act of trust—trusting in God in spite of our doubts and confusions. The opposite of faith is certainty, not doubt. It is not about a well-ordered set of convictions and an entirely satisfying relationship with a clear God. In fact, we need uncertainty and doubt. “If there is no room for doubt,” Frederick Buechner once said, “there is no room for me.”

Something bad happens to religion that has no room for doubt. It becomes arrogant, rigid, all about self and certainty. Scholar of religion Karen Armstrong says in fact that the problem with religion today is certitude, the absolute certainty that one is right, in full possession of the truth. Absolute certainty gave us 9/11. We need less certainty, more mystery, more trust, more humility.

After all, Jesus put no preconditions on his disciples about believing certain things. ‘Follow me,’ he says, not, ‘believe these things.’ Live my way, learn what trusting a mysterious, loving God in this complex world means. That’s what faith means—taking the step to come along—back to church, into a class or ministry, into an AA meeting, offering forgiveness in spite of your uncertainty or anger. Faith is trusting, risking, betting on the love and power of God, and then finding the confirmation along the way.

In our gospel lesson for today Jesus has been explaining just what it will take to follow him—loving your enemy, forgiving seventy times seven. It sounds overwhelming, and so the disciples cry out in exasperation, “Increase our faith!” Make our faith stronger, clearer, more confident!

But did you catch his response? “If you had faith the size of a mustard seed you could say to this mulberry tree, ‘Be uprooted and planted in the sea,’ and it would obey you.” A mustard seed is infinitesimally small. But if you have even that much faith, you can move a huge mulberry tree, and in Matthew’s gospel Jesus says you could move mountains. What matters is not how big and strong your faith is, but what God can do with even the smallest amount of trust we can offer.

And that, we now see, was Mother Teresa’s story. It is moving and sometimes heartbreaking to read her accounts of her broken, limping faith, and the long dryness and sense of God’s absence. In her letters she is no super-human saint, but one of us, a good and faithful woman doing what she believed Jesus has called her to do, wrestling with her own darkness and despair. And yet, what great good she did.

I found myself asking questions as I read the account of her inner struggles. Should she have stayed so long in Calcutta among the desperately poor? Might she have had a deeper sense of God’s presence if she had moved on to a less exhausting ministry? And yet, in giving up even the sense of assurance and joy in God’s presence, she touched the lives of so many thousands of suffering people. It looks as if she sacrificed even her spiritual life for the sake of those she served.

We Christians believe that a great, mysterious God is continually seeking us and speaking to us through the experiences of our world—in the beauty of nature, the comments of a friend, the experience of delight in a child, in the suffering we see in the news, in the guilt at our failure, and above all in the bread and wine and Scriptures, where Christ feeds us with his life. And presence, absence, silence, mystery, life in community, all make up the ongoing journey into discovering God’s love for us.

“Increase our faith!” we probably all would say. But it only takes a mustard’s seed worth, not something heroic and demanding up front. Just a little at a time, enough to keep on the journey, enough to keep growing, to keep listening for God’s leading, and enough to be doing the only thing that really matters, learning how to love. With that mustard seed faith Mother Teresa poured herself out in love, and it moved mulberry trees and mountains. That’s something we can do too.