“Even where the Faith is preserved men pursue wealth and power inordinately. Where the Faith is lost they pursue nothing else.”

Address to the European Parliament (2015)
Context: People thrive where there is mutual respect. Civilisation is built on it. Futures are better for it.
But co-existence must be made, and made again, in every generation. The common good is defended only by vigilance and action. This means more than security measures. Humanity must arm itself with ideas, with justice and with economic and social inclusion.
Today, these challenges have special importance. Our world faces an assault by terrorists with ruthless ambition. The motive is not faith, it is power; power pursued by ripping countries and communities apart in sectarian conflicts, and inflicting suffering across the world.

Letter to John Ching Hsiung Wu (1924), published in Justice Oliver Wendell Holmes: His Book Notices and Uncollected Letters and Papers (1936) by Harry Clair Shriver, p. 175.
1920s

Source: A Voice in the Wind

Source: The Case for Faith: A Journalist Investigates the Toughest Objections to Christianity

Source: A Chance to Die: The Life and Legacy of Amy Carmichael

Source: By the River Piedra I Sat Down and Wept

"Religious Perplexities" (1922), his Hibbert Lecture.

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?