“My dead go on suffering in me the pain of living.”

Letter from Naples, Italy to Otto Grautoff (1896); as quoted in A Gorgon's Mask: The Mother in Thomas Mann's Fiction (2005) by Lewis A. Lawson, p. 34
Context: I think of my suffering, of the problem of my suffering. What am I suffering from? From knowledge — is it going to destroy me? What am I suffering from? From sexuality — is it going to destroy me? How I hate it, this knowledge which forces even art to join it! How I hate it, this sensuality, which claims everything fine and good is its consequence and effect. Alas, it is the poison that lurks in everything fine and good! — How am I to free myself of knowledge? By religion? How am I to free myself of sexuality? By eating rice?

Source: Vorkosigan Saga, Barrayar (1991)

Source: Isle of the Dead (1969), Chapter 3 (p. 61)

On her dark night of spiritual desolation amidst devotion, in a letter addressed to Jesus, as quoted in Mother Teresa: Come Be My Light (2007) edited by Father Brian Kolodiejchuk, p. 192; regarding this quote, Fr. Kolodiejchuk writes: "...when addressing Jesus — that is, in prayer — she could express herself with ease. Fufilling her confessor's request, she sent to him a letter addressed to Jesus, enclosing it with her letter dated September 3, 1959." https://books.google.com/books?id=P4cqT0nK_joC&pg=PA192&dq=%22when+addressing+Jesus+-+that+is,+in+prayer+-+she+could+express+herself+%22&hl=en&sa=X&ved=0ahUKEwjk0IOm5vTOAhVF1x4KHYdRDE4Q6AEIHDAA#v=onepage&q=%22when%20addressing%20Jesus%20-%20that%20is%2C%20in%20prayer%20-%20she%20could%20express%20herself%20%22&f=false
1950s
Context: My own Jesus,
They say people in hell suffer eternal pain because of the loss of God – they would go through all that suffering if they had just a little hope of possessing God. 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 (Jesus, please forgive my blasphemies, I have been told to write everything). That darkness that surrounds me on all sides. I can’t lift my soul to God – no light or inspiration enters my soul. I speak of love for souls, of tender love for God, words pass through my words sic, lips], and I long with a deep longing to believe in them! What do I labour for? If there be no God—there can be no soul.—If there is no soul then Jesus—You also are not true... Jesus don't let my soul be deceived—nor let me deceive anyone. In the call You said that I would have to suffer much.—Ten years—my Jesus, You have done to me according to Your will—and Jesus hear my prayer—if this pleases You—if my pain and suffering—my darkness and separation gives You a drop of consolation—my own Jesus, do with me as You wish—as long as You wish, without a single glance at my feelings and pain... I beg of You only one thing—please do not take the trouble to return soon.—I am ready to wait for You for all eternity.

At A Child's Grave (1882)
Context: The dead do not suffer. And if they live again, their lives will surely be as good as ours. We have no fear. We are all children of the same mother, and the same fate awaits us all.
We, too, have our religion, and it is this: Help for the living, hope for the dead.

Source: My Friend Leonard

Source: Norwegian Wood

Source: The Dresden Files, White Night (2007), Chapter 31

Undated letter indicating that, at least at times, Mother Teresa's theological doubts were strong enough to be regarded as Christian atheism, reported by Time (9 March 2007) http://time.com/4126238/mother-teresas-crisis-of-faith/,and quoted in "Was Mother Teresa an atheist?", in The Guardian (24 August 2007) http://www.theguardian.com/commentisfree/2007/aug/24/wasmotherteresaanatheist
2000s
Context: Lord, my God, who am I that You should forsake me? The Child of your 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–no, No One.–Alone … Where is my Faith–even deep down right in there is nothing, but emptiness & darkness–My God–how painful is this unknown pain–I have no Faith–I dare not utter the words & thoughts that crowd in my heart–& make me suffer untold agony. So many unanswered questions live within me afraid to uncover them–because of the blasphemy–If there be God –please forgive me–When I try to raise my thoughts to Heaven–there is such convicting emptiness that those very thoughts return like sharp knives & hurt my very soul.–I am told God loves me–and yet the reality of darkness & coldness & emptiness is so great that nothing touches my soul. Did I make a mistake in surrendering blindly to the Call of the Sacred Heart?